Harrison Ford has been pretty vocal about the fact that he's kind of over Star Wars. They got him to return to for Star Wars: The Force Awakens likely because they promised to kill him off once and for good. The problem with being a character in a science-fiction story is that dying doesn't mean you're not coming back in some capacity. Ford was recently on the cover of GQ and they asked him if he was ever going to come back to the franchise.
GQ: When it comes to 'Star Wars', given the nature of science fiction, are you absolutely, incontrovertibly—
GQ: —finished with 'Star Wars'?
Ford: Um, I mean, I'm finished with Star Wars if Star Wars is finished with me.
GQ: And if 'Star Wars' isn't finished with you?
Ford: I can't imagine it. But it is science fiction. I'd rather not. You know, at this point I'd rather do something else. Just because it's more interesting to do something new.
I think it's time to just let it go. Ford doesn't want to come back again, and the amount of handwaving they would have to do to justify bringing him back now that Carrie Fisher has passed seems like way too much work. He wants to move on, so let's let him move on. We got another Star Wars out of him, and we're getting another Blade Runner and another Indiana Jones. Enough is enough.
Summary: Having taken her first steps into a larger world in Star Wars: The Force Awakens (2015), Rey continues her epic journey with Finn, Poe and Luke Skywalker in the next chapter of the saga.
Star Wars: The Last Jedi, directed by Rian Johnson, stars Daisy Ridley, John Boyega, Mark Hamill, Oscar Isaac, Carrie Fisher, and Adam Driver. It will be released on December 15th.