Where do their stories go? The "hook" for Rey is "who are you." That's solved. Finn's story can possibly be continued if he is indeed Force sensitive; Poe is a big shot with the new government, presumably. But without the First Order to battle, do we really want a story about setting up a new...
I imagine so. Anytime Ridley and Boyega are interviewed, they say they're done, based on what I remember. I don't recall if Isaac has the same reaction.