"We're going to have HTML5 for the next twenty years..."<p>Everybody's going to get up to speed with implementation of HTML5 and then ... stop? The story of HTML5 so far has been a mix of browsers chasing/leading the standards. In other words, the standards and the browsers are evolving together rapidly. I don't see why that would stop anytime soon. Certainly all this innovation won't ground to a halt when HTML5 submits their final release to the W3C (or whatever the next "formal" step is at this point).<p>Will there be some instance of an installed browser today that will still be running on a machine somewhere in 20 years? Well, probably... but remember that guy a couple of years ago that still had a CP/M system running his business? He wasn't holding anybody back.<p>And once everybody's on modern, standards-compliant browsers (and thus there's less friction for upgrading, i.e. there's no more "all our corporate apps only run in IE6"), I expect far more people will upgrade far more often. The web is at a really, really exciting time if you ask me.<p>So: non-Flash web technologies can reliably handle some percentage of Flash use cases today. Certainly more than a couple of years ago, and that appears to be about to go up again a lot more as HTML5 sweeps across the web. The number of use cases that require Flash are going to continue to get smaller and smaller over time. When will Flash be utterly irrelevant to the average user? I don't know. But WAY less than 20 years from now.