It's not clear on what angular 2.0 will be based, the more the angular team talks the unclearer it is :
http://i.imgur.com/upcrFbi.png
this is a slide from ngconf.
http://i.imgur.com/upcrFbi.png
this is a slide from ngconf.
Also, Angular 2.0 is going to be written in TypeScript (which will be compiled to plain JS) but you can use ES5, ES6, TypeScript or Dart depending on what you want to use for your application.