Nice conclusion to the show... unless there's an after.
A 12 eps conclusion would have worked, less rushed and more supporting cast. After all supporting characters are what makes that show whole.
Regarding an after, maybe that scene in the ED last season is enough. Not easy to depict Stanford environnement, even more for Japanese people with no experience of the place. And you can't have your characters all move there.
You could offer a twist, or find a way to only focus on out campus life, but the school setting was also a strong part of the show.