There are a couple trending topics about the future of Star Wars movies and the inevitable fate of the Star Wars Rebels crew.
Looking at how Disney handles their licensed properties, i.e. Marvel and Princesses, they have historically added more character, rather than remove them. Avengers, Guardians of the Galaxy, Agents of SHIELD, and coming soon, the New Defenders. With princesses, there's an endless stream of movies with crossovers on the TV shows.
It's smart business. It's more stuff to sell. More stories to tell. More variety to draw in more fans.
Disney is trying to expand the Star Wars storylines past the Skywalker family and to the rest of the galaxy, not reduce them.
Granted, Disney kills characters from time-to-time, but to wipe out all the Jedi in Phoenix Cell counters what they've done with other properties.
Then again, this could be just wishful thinking, because I really don't want to see the beloved Rebels characters wiped out and explain that to younglings.