There were glimmers here and there afterwards (the Cleansing for instance), but for the most part, all of the memorable stuff went down in the first six books.
Don't get me wrong, I like Sanderson's books....its just that he is no RJ. His trilogy broke some major rules, and really just kind of....dribbled off. Sure, it wasn't the close to the story that I wanted, but then the author I wanted to end it died. It would be much akin to "The Return of the King" being done by someone else.
As for being removed from Canon-status...I'm not sure. It's not like they are Fanfic or something. They are published with the full approval (and even involvement) of his writing/publishing team....and his notes.
~Jeordam
Saving the Princess, Humanity, or the World-Entire since 1985