ActionScript 3 is not going away, and we are not removing anything from it based on the recent decisions. We will continue to track the ECMAScript specifications, but as we always have, we will innovate and push the web forward when possible (just as we have done in the past).
Dan Smith, one of the Adobe engineers who works on Tamarin sums it up the best in a comment to John Resig's post:
Today's announcement doesn't affect the current definition of ActionScript at all. Innnovation (sic) typically leads standards and AS has done so for years - conditional compilation, vectors, classes, etc are available today.
Dave McAllistor (also from Adobe) has also posted more in-depth thoughts on his blog.
The nature of standards are that they are slow, and they follow implementation. Standards codify, they do not innovate. From this, it follows that in order for there to be progress on the web, companies and other organizations must be willing to push the web in new ways. Indeed, Alex Russel (of Dojo) comments on this in a post on the failure of the W3C:
To get a better future, not only do we need a return to "the browser wars", we need to applaud and use the hell out of "non-standard" features until such time as there’s a standard to cover equivalent functionality. Non-standard features are the future, and suggesting that they are somehow "bad" is to work against your own self-interest.
While Alex has been focusing a lot of his hopes and efforts on Google Gears, the Flash Player is in the same position. Indeed, the Flash Player has consistently pushed innovation on the web, from bringing animation and motion to the web, to advanced scripting capabilities, to video, and more robust programming runtimes.
It should therefore be no surprise that the HTML 5 draft reads like a laundry list of past Flash features (video, audio, sockets, drawing apis, etc...).
To sum up, ActionScript 3 isn't changing and we are not going to dumb down future versions or ActionScript. We are going to continue to innovate on the web with the Flash Player, and push the web forward, as we have done for over a decade.