The core repertoire hasn't really changed but the boundaries get further and further out. It's like "classical" music. Pianists must learn the 2 part inventions, they're an essential part of the tradition.

Big band is hard to learn from. The large ensembles like Basie's and Duke's have persisted in popularity, but classic "big band" are very much of their time.

The bebop guys will always occupy the position in jazz that Bach occupies in "classical". They're foundational musicians in a continuous tradition and one learns a lot about the music by studying them.

By "canon" do you mean respected musicians? Or do you mean that PLUS players whose work is considered essential to learning how to play the music? The answers will be different. Keith Jarrett is great and esteemed but unless you want to sound like Keith Jarrett, he's not essential to study.