Keep in mind that they don't keep progressing linearly forever because of the nature of the service that's attempting to be provided -- neither are far off from being able to do basically all the things that can be done on a 2D panel attached to a speaker or two: interface device input, 2D/3D animation, sound effects/music, a bit of local persistence, access to the videocamera,... what else is there? I'm not sure of each's multitouch API, if any, but, really, there's not that much more beyond those things that HAS to be implemented for the <i>vast</i> majority of web pages and apps to fully function. Support for accelerometers and other such devices would be nice, but is hardly important to reading the New York Times or the other 99.999% of things people do/want to do with the web. Perhaps in 2030 there'll be argument about whether the web- or proprietary-way has the best support for holographic 3D displays or 360-channel surround sound, etc., but those and many other things that the two technologies don't support today seem likely to continue to overall be niche things. In other words, things whose proper role is a <i>plug-in</i>, not a vital part of many pages' experience. That's fine: there's going to be a role for plug-ins for a long, long time, perhaps forever. But, the fundamentals? We're getting pretty close to having them covered.<p>Also, I think it's well worth taking a good look at HTML5's rate of progress over the years. A huge chunk of the HTML5 effort has been toward just standardizing the response to the tag soup that is out there. That work is essentially done and doesn't have to be repeated. Just in the last year or two have things really taken off as far as adding new functionality to browsers and example pages, and it's only been in the last couple of months that a few actual commercial pages have started to use these things. In large part, that's because the web has been <i>stuck</i> for most of a decade because of IE stagnation. [Also note that the rest of the browser/platform vendors didn't seem to have a good mechanism to rapidly innovate together on until the HTML5 effort came together. I don't expect that that diplomatic work will have to be done again, either.] The web platform after the IE stagnation seems likely to move much faster toward covering the gaps that remain in the web platform.