I do think, in time, HTML 5 will take some market share from Flash, Silverlight, and JavaFX. However, it's hard to see HTML being relevant for the better part of the next decade. It's 2009 and we're still dealing with IE 6, which was released in, what, 2001? The slow and painful death of browsers will keep HTML 5 from true penetration for some time.

A good comparison would be the debate over desktop vs RIA and web apps.

In terms of the depth and power of the development environment, native still beats RIA by a long way – but the majority of software is low-hanging fruit, which can be implemented as a web app.

The same will hold true with HTML 5 – Flash may maintain a richer API, but a lot of apps won’t need it.

I think where the battle will be decided is in the mobile space, where neither IE or Flash have much lock-in. So far Adobe’s not proven they can deliver an HTML 5 beating version of Flash on any of the new smartphones, but most of them have WebKit powered browsers implementing (some) HTML 5 features.

As I see it, the main problem with HTML5 competing with the usual suspects of browser plugins is the constant thorn-in-our-side problem we've always had and will most likely always have...

Internet Explorer

When I make a Flash video I have a high level of confidence that the video app will work and look much the same across any platform that supports that version of Flash, regardless of browser or OS. It will be a long time before I instill that level of trust in HTML5.

We will eventually have this high level of confidence for "modern" browsers supporting HTML5 but I doubt we will ever reach that for IE. Especially since I get the feeling that most people in the industry do not consider IE a "modern" browser, even IE8.

I for one, do not.

And as long as IE6 and IE7 controls a decent percentage of the browser market share then it will never happen. Unless MS will force everyone on IE6 to update and IE7 gets all the same HTML5 features that IE8 gets. Even better, force all versions of IE to the latest version, which we all know will never happen.

Personally, I'm excited about the possibilities that HTML5 and CSS3 teases us with, but I'm doubting I will ever really use them during my career as a web designer. Maybe my daughter can learn about the cool stuff when she goes to college, in about fourteen years.

the poll needs to be better refined:
First, what time frame are speaking about? In the short term (next 2-3yrs), there is no way HTML5 will be able to overcome well entrenched plugins with tons of productivity tools already built and on the market.
To think otherwise is like hoping in 2006 that IE6 would disappear soon. :)

Second, HTML5 is rather late to come on and provide anything disruptive. IE will lag, in order to support Silverlight. Chrome and Firefox (maybe) will have an incentive to push things forward. As you can see, with a fractured effort, there will be plenty of delays and back and forths.

I'm a little torn on this issue because I know that browsers, in particular IE, are going to hold back the adoption rate of HTML5. However, I feel like there is an entire generation of of apps which we already depend on which will need to draw a line in the sand as they advance in feature sets. In particular I'm thinking about the transition from GMail to something like Google Wave (which I understand to be built on HTML5). Consider also if a site like Facebook does an HTML5 rewrite. Previously we have not had social media ( which could be seen as an agent of peer pressure ), to spur on these advances. 1) It didn't exist and 2) It worked with old browsers. Now consider if Google Wave and this hypothetical HTML5-Facebook dropped tomorrow. How fast do you think people would jump on those new products and how quickly do you think the whole thing could tip?

@Rob - Excellent point but it likely won't happen. Why? Because you're asking businesses to essentially abandon their market share in the hopes that the audience will perform the desired task, which MIGHT restore their market share. If Facebook did such a thing so that it didn't work for a large number of people then those people would go elsewhere. That's one reason we still have IE6, because companies still support it and none of the big boys want to pull the trigger first.

We could propose that everyone make an alternate site that supports the new stuff and slowly try to convince everyone to switch to the browsers of choice. But that would double the work for these companies with no guarantee that it would succeed. Plus you're still dealing with the same problem, if a site doesn't work or doesn't offer features someone wants because of the browser they are currently using then that person is more likely to change sites than to change browsers.

Unfortunately, I feel, that the future of HTML5 adoption is in the hands of Microsoft and, to some degree, to the other browser vendors. MS would need to update IE8 in a timely fashion (fat chance), update IE7 as well (doubtful) and force an update on all IE6 users (never happen). Oh, also quit lying about their browser and how it compares to other browsers. The other browser vendors need to increase the marketing of their products in an attempt to get people off the IE fiasco.

As long as browser manufacturers continue to do things differently and not adhere to the same set of standards, Flash, Silverlight or any plugins will be the best method for consistent cross browser experiences. On top of that, the tool set to support designers & coders doing Flash and SL development is far more mature than HTML development.

Sorry, but I find it quite ridiculous to speculate about something which will be fully (perhaps ...) available in 5+ years! Who knows what Flash/Flex, Silverlight, etc. will offer by then, especially with the current competition between Adobe, MS et al. which is fantastic for us developers.

Is anyone already discussing Ubuntu 13, Windows 9.5 or Firefox 5? No? So, why then HTML5? And why does one of the technologies have to 'kill' one or several of the others?
Flash and HTML have been coexisting for quite some years now. I love Flash/Flex. If someone else has a different opinion, he/she/it does not have to develop for it and does not have visit web sites with Flash content. Where's the problem?

@Travis - I think your second paragraph gets at what I'm trying to describe. Google Wave already exists, and they've started handing out developer accounts. When they release it in a year or so they're obviously not going to shut down GMail, but instead run Wave in parallel; and the features which are available to the Wave users will simply not be available to the GMail users.

Returning to the Facebook model...
In the current climate, if I update my browser or start using Firefox instead of IE it really doesn't have an affect on my friends/coworkers/etc. So there's little incentive for me to suggest that they upgrade or switch their browser as well. All of that changes though if the alt-Facebook comes out with some great new features which I can't use with my best friend because they're still running IE6. In this new scenario there is an incentive for me to convince them to change.

In the current paradigm there is no imperative reason to switch to a modern browser because everything is forced to comply with older tech. But when that becomes feasibly impossible then businesses will have to make these alternate pages/services. And since I don't anticipate that Google or Facebook or any of the other big names are going to wait for their competitors to beat them to the punch when it comes to HTML5, you can bet that you'll be seeing these alternate services soon.

@Rob - I see your point but I don't see Google Wave as a good example of two sites, one HTML4 and the other HTML5. GMail is one thing, Wave is another. Yes, they are similar but Wave goes way beyond what GMail does to the point I would say they are not intended for the same market. GMail is an email tool, Wave is a collaborative tool. I'm willing to bet most of the people who would use Wave are already using a browser compatible with it or soon will be. Plus Google is starting from scratch with Wave so that is an advantage for them to use HTML5 from the start. How about we ask Facebook, Yahoo Mail, Flicker, Twitter and whatever else to support a HTML4 and HTML5 version of their current applications at the same time?

Facebook; if you are using a feature that is dependent on your browser that your friend cannot participate with, then it does affect him. At that point he has a choice, update to use the new feature or not to update. Wait, update? I should say completely change his browser because if he's an IE user then he will almost always be left out with HTML5/CSS3 features. You may be able to convince him of the advantages to changing but that doesn't necessarily mean he will. And again, are you asking Facebook to risk market share for implementing features only a portion of their audience can access? Plus I think you are completely ignoring the costs of maintaining two complex websites that serve much the same purpose. Take the annoyance of maintaining multiple style sheets for different browsers and multiply by who knows what.

Now, once enough browsers support the proper amount of HTML5 features and Google completely revamped EVERYTHING they offer as requiring those features to work, then some interesting things would start to happen. Unfortunately one of them would be a sudden drop in their market share. They would have to do the development in parallel (as you suggest) and I doubt even Google has the resources to maintain such a thing.

As long as the old tech maintains decent market share no business in its right mind will completely ignore it. As long as that old tech is around it will never be feasibly impossible to maintain. If you can make a web page that works for IE6/IE7 now, you can do the same fifteen years from now. The problem with that is the new tech will stagnate while everyone waits on Microsoft.

I hope that HTML5/CSS3 works out better than I expect. But as long as enough people insist on using IE then the HTML5/CSS3 platform has a long, difficult road ahead of it. Unless, that is, Microsoft decides to catch up with the rest of us.

If Google supports the video tag in Chrome and switches YouTube from Flash video (or support both) I suspect they could swing a sizeable market.

They could do it by making some options (download videos say) only available if you use Chrome or an HTML5 compatible browser.

As a developer all I care is how easy it is to code a web app, which is why I give the edge to RIAs (SilverLight in particular).

Why would I want to code an app in HTML / Javascript? HTML was designed as a set of documentation tags instead of an app framework. Think of the back / forward buttons there: Anyone who codes quite a bit of web apps knows those buttons can mess things up. Why? Well HTML was designed as document. They didn't realize those buttons can completely disrupt a workflow. You see it's an awkward environment for apps. This HTML 5 thing is forcing the issue here.

Due to lack of serious framework support, Javascript coders have to do a lot of heavy lifting to achieve what RIAs readily support right out of box. The lameness doesn't stop there yet. A serious web app usually is a 3-tier application. W/ SilverLight and JavaFX, you only need to master one framework and then are good to go all tiers. W/ HTML / Javascript, you have the GUI tier only. But what runs on the server tier is PHP, Java, Ruby, Python, .Net ... everything but Javascript, which means you again have to do the heavy lifting to convert back and force any non-trivial objects between the client and server. Such hassle doesn't attract people.

Google can put out as much lip service as they want on this HTML 5 thing. I'm not buying it b/c it's clearly less productive compared w/ what RIAs offer.

I recommend this article:

http://www.davidtucker.net/2009/06/19/an-honest-open-discussion-on-web-standards-and-html-5/

Pointless poll, way to early

Johan: "If Google supports the video tag in Chrome and switches YouTube from Flash video (or support both) I suspect they could swing a sizeable market."

The problem is that there's no standard for video codecs, meaning each browser vendor will decide on what codecs to support if any. Which means in order for the video tag to work, Google or any other company using HTML5 video tag will have to supply multiple versions of the video in a variety of codecs. This has the potential to get even messier, depending on what codecs (if any) various mobile devices support. For Google, this would get very expensive for a product like YouTube that is already bleeding millions.

Also since there's no codex detection for browsers, assumptions will have to be made with what codex the user might have based on browser or operating system. Any users who edit or mask their browser's user agent will likely run into problems viewing HTML5 video.

Meanwhile, here's still missing features from the video tag that is currently in the Flash Player like full-screen and HD video.

The other problem with browsers and video codec is that there's always new ones with better quality for lower CPU and file size. Locking codecs to browsers will mean a slower upgrade path to new codecs compared to using a plugin. Imagine IE6 users being forced to use an old video codec from 2001 when IE6 came out, if the video tag existed back then, compared to what's available today in Flash and Silverlight.

The end result is that I doubt YouTube will switch over to 100% HTML5 site anytime soon.

As for Google Wave, note that some of the new functionality is not coming from HTML5, but using the Google Gears plugin. Which I mention as a lot of people don't seem to realize that and think it's all HTML5.

Also note that Google have mentioned that they will support IE7 & IE8 with Google Wave, but despite Google's vast resources, they have been quoted that they have a long way to go to get IE support. Meaning it's time consuming and expensive to support all the major browsers with cutting edge functionality, when it can be done a lot cheaper with a plugin. A company like Google with vast resources they can afford to go that way but even then it will take them a long time to do so, while smaller companies will likely want to use that time and money for more features using a plugin.

As for the whole browser debate and getting people to upgrade their browser, here's a video that puts it in perspective, where the average person doesn't even know what a browser is let alone which browser they use:
http://www.youtube.com/watch?v=o4MwTvtyrUQ

I think HTML 5 will take market share from silverlight, JavaFX, Ajax and Processing, not Flash. Flash is lead Rich media tech and has visioned over 10 years. The other Rich media solution just jumped on few years ago from Flash's popularity. Now, HTML5 joined another track line of Rich Media. It won't effect Flash's web penetration. It will kill another minor Rich Media tech behind.

@Matthew - Hear, Hear!

I had forgotten that Wave was going to require a plugin to provide some of its features.

The debate about which video codec to support is another problem that will take time to work out before we can rely on it, for the very reasons you give.

Debates are great but if they took much of our time, they may turn to be waste of time.
Compettition is great, it offers possibilities for developers, but a lot of competition may offer tools that only make developers waste time in choosing.
HTML5 carrying the HTML word, goes more for stantards which fights against innovation and better tools. Things I have seen in flash, unity3D and other tools wont be done in HTML7,
If adobe builds a native HTML/CSS rendering engine (we dont need all), may be this debate will be over.
and HTML5 can never kill (a word I really hate) flash , because they is more than stantards in flash.

I've written applications using Ajax, Flex and Silverlight. I have to say I hate Javascript. Javascript is hands down the worst programming language I find myself using. After using Flex and Silverlight there is no way I'm going back to using Javascript if I can avoid it. Unless HTML 5 comes packaged with a better language that supports application development then you can count me out. I don't have a religious affiliation to open standards; instead I use the technologies that work best for the application I'm developing.

A while back there was a statement from Microsoft about Silverlight being installed on more browsers than firefox, chrome and safari combined. At the time naysayers just poo-pooed it, saying it was comparing apples to oranges etc. However this discussion around HTML5 vs plugins is really where it is at and it makes that comparison (if accurate) completely relevant.

Nobody has mentioned something that has a high priority to me as a developer - code protection.

Isn't SWF the only compiled format? (I know it can be decompiled, but from personal experience this often produces unuseable output, or obsifucated code that's enough of a disincentive not to bother).

If the developers can't protect their IP, what incentive do they have?

The very reason I became a Flash designer (now a Flex developer), like ten years ago, is that I got tired of waiting around for browsers to get their act together and advance the technology so I didn't have to spend half my time catering to the lowest common denominator capability. Macromedia wasn't waiting, and neither is Adobe. HTML 5 is now a great new standard, but so what? Not all the browsers use it, or will for quite some time. And now HTML 5 is supposedly a "Flash killer"? What, I'm going to wait around for another 5 years so I can do HTML 5 in all browsers what Flash used to do like five years ago? I don't think so.

well said Joe. Flex/Flash is a mature technology that can be used today. Tomorrow...who knows...but competition is welcome!

Only in the last year or so has there been a concerted effort by Apple and Google to challenge on the browser front. Considering the three up and coming mobile devices (pre, iphone, android) run webkit and not flash/silverlight...HTML is the only cross platform solution. Incremental updates to HTML will be enough to forestall flash/silverlight dominance. Once IE browser dips below 50%, then things become really interesting. In Europe, Win7 will not ship with IE, so I anticipate a big shift away from IE in the near future 2-3 years.

HTML5 VS FLASH: As JMC told SWF files has got a good protection against lamers that cut-and-paste code around internet.

Silverlight: I do not know anybody who uses it.

JavaFX: I have done some Java applets in the past, but I stopped because the WEB request Flash, and I don't think to came back to JavaFX.

Also everyone has got a Flash player on his PC (also my phone has got a light version!), and the last version 10.0 is very optimized.

So, FOR ME, for next 5 - 10 years Flash will remain the leader without doubt.

HTML 5 is supposedly a "flash killer?" No way. Flash is a double edged sword. It is used to play videos but Flash is also used to create animations and business presentations. HTML 5 plays the video - in some but not all browsers - but it doesn't create an animation or a presentation for you. Millions of businesses use Dreamweaver and Flash for more than just watching videos. Business has already jumped on the Flash bandwagon. So Flash has more uses that HTML 5 cannot compete with. That sets HTML 5 lower than Flash in being useful. With all the squabbling over codecs it makes HTML 5 a novelty bordering on being useless in both short term and long run.

I believe that new browsers (HTML 5) will be adopted far faster than previous browser roll outs due to the fact that people will see web apps comming out that they are excited about and will only be able to use if they upgrade. Of course there will always be a percentage of the population reluctant to upgrade, but those people are not the same people that desire to use things created using Flash and the like anyways.