Personally I believe that once Dart development is finished, Google will roll the good parts of the server-side pieces to Go and frontend into ATScript/Angular 2.0.
Supposedly one of the reasons ATScript isn't just a small fork of TypeScript and instead is an oddly reimplemented TypeScript built on top of Traceur is so that ATScript can still compile to Dart, so apparently at least a few people on Angular 2.0 still like Dart...