This is a good question. Chrome features NaCL which allows apps to run at native speed and very securely. Once a NEXE is compiled (using any language that has a compiler that can produce a NEXE), the app can be put on the web and leverage HTML5, and web gl to provide a traditional OS experience. No more javascript only apps.

Unity 3D the gaming development environment, supports NaCl and as such, you can expect that many games will be ported to the web. Here's a video of a working game: Lego Star Wars 3D

http://www.youtube.com/watch?v=qRrX7Rb1PdA