>>37
Why? Partly because of the video codec snafu and related shenanigans. Partly because there's a lot of JS hate, and HTML5 has more use for JS than previous versions. (These people are getting it backwards though; the problems with JS in the browser are less severe now that you can build rich sites with smaller DOM trees.)
There's no need to look
forward though, unless you're speaking of proliferation. WegGL enabled HTML5-capable browsers are available right now.