"HTML5 is going to evolve much faster than ActionScript."

As written, this statement is wrong.

Adroit developers are picking up HTML5's JS API's with more enthusiasm than they have ActionScript, and they'll push those API's to their limits, as they have done with the DOM API's. But the technology itself--the underlying standards--must necessarily evolve at a slower pace than a proprietary language like ActionScript. Browser vendors haven't quite caught up with HTML5's growth yet; once the the spec's final, W3C won't be moving the goalpost out any further for a long time.