I really don't like this proposal. For me, HTML is the markup for the design of the page, while JavaScript makes up the logic. While some frameworks break this, they are strictly opt-in, and they still offer a bit of separation of duties. I'd rather see the HTML standard stay markup-focus for now.
HTML is the structure, CSS is the look, and JavaScript is the logic. With a strict XHTML style you can further enforce this by removing former standards which don't follow that design (e.g. OnClick="" etc).
HTML5 is alright, but I'd like to see a strict HTML5 which bans a ton of classic HTML4.1 elements completely and also follows XHTML's much more logical style (and bans things like
which make no sense).
I understand why they went the way they did (backwards compatibility mostly), but feel like the web would be in a better place ten years from now if a strict spec for at least HTML was commonly used.