1. I agree, that would be useful.
2. You have to consider what HTML/Java is capable of right now. I don't think that's really possible.
3. Dynamic filters would be too processor intensive and would run very slowly on mobile devices. The idea is that you develop it once for all platforms and this would basically would ruin any chances of it running smoothly everywhere.
4. Agree 100%. This wouldn't even be that hard, at least for H.264.
5. Again, this sort of feature would be too processor intensive.
2. Bummer. Figuring out a way to support Z depth would be sexy as hell.
3. While dynamic filters would be too intense for mobile platforms, they could most certainly perform just fine on desktop / laptop platforms - the mobile versions are the "diet coke"
5. Really? I wouldn't think that dynamic masking would be that processor intensive, but then again, my experience stems from mainly Silverlight and Flash.
That said, I keep seeing more and more amaziing things done with javascipt. And there is already some limited filter support svg images (on some browsers) So maybe soft, feathered masks, blurs, glows, and ink effects (add, lighten, multiply) will arrive sooner rather than later.