The future is here, but we don't know how to deal with it yet. How we currently create web applications is so fundamentally different... that it's almost like learning from scratch. It still doesn't tell you how to construct your application (aside from using components, of course). You'll still have some type of "application wide script", I think, to do stuff like routing.

I see it more as a potentially native impl of MVVM which is currently done in the application layer. the speed optimization is important if we want to have UIs as complex as, say, an IDE in the browser, which is pretty clearly where we are headed this decade.

Light Table is pretty darn fast and that's using the regular old html/js/css we have now. :)

I think the parent of your comment meant: "the speed optimization is important if we want to have UIs as complex as an IDE _built with these new APIs_" --because polyfills do lots of work to emulate browser features.

Both the native ShadowDOM implementation in Chrome/Canary and the ShadowDOMPolyfill support reprojection.