I am now fairly confident based on evidence I don’t wish to make public at this point that Apple is planning new (likely UIKit) Music, Podcasts, perhaps even Books, apps for macOS, to join the new TV app. I expect the four to be the next wave of Marzipan apps. Grain of salt, etc.
I hope they still keep iTunes around. (I assume) I’m one of the few people who actually like it.