What's the name of the Angular component for login?
The difficulties in creating a semi or fully decoupled site isn't in the RESTful part. Spitting out JSON is now covered by several modules, including RESTful which aims for a "best practices" solution.
One of the real problems, though, is how to prevent us, the community, from re-inventing the wheel over and over again. Basically, how do we package our frontend code similarly to how we package our generic backend code - AKA "modules". I discussed these problems, and offered some solutions in my "BoF" persentation: