Wouldn’t it make a lot of sense for “What comes next” to be the new-canon version of the Legends Thrawn trilogy? They’ve introduced Thrawn, they’ve introduced Noghri, and only one film left in the ST makes it a perfect time to start telling post-ROTJ stories.
It’s possible, granted Thrawn survives Rebels (we have one episode left to see). There’s already some post-ROTJ content (Battlefront 2017, the Aftermath series) that a Thrawn series would have to be made compatible with, and I don’t know how feasible that is.