Major spoilers ahead for Star Wars: The Last Jedi. You've been warned!
Although it was released nearly a month ago, cinephiles and Star Wars fans alike haven't stopped dissecting and discussing Star Wars: The Last Jedi. Rian Johnson's sequel subverted fan expectations, and provided a capsulated story that drastically changed each of the characters. Perhaps no character went through more changes than Mark Hamill's iconic Luke Skywalker. Luke's journey throughout the film was of isolation and self-loathing, but he ultimately ended up coming through and inspiring the future of The Resistance and The Force. Johnson was recently asked about whether he could return in Episode IX as a Force Ghost, and therefore allow Hamill to have another appearance in the franchise. He said,
I don't know where the next movie is going to go. J.J. (Abrams) and Chris Terrio are writing it right now. But it seemed like the potential of Luke crossing into new realm --- that offers exciting possibilities for the role he plays in the coming chapter. No one's ever really gone.
While Rian Johnson doesn't seem especially cued into the writing process of Episode IX, he certainly seems to think that Luke's Force Ghost could pop up in the next film. And considering the precedent set by the previous movies, including The Last Jedi, it would make total sense.
Rian Johnson's comments to Variety seem to point out how Luke's physical death doesn't necessarily mean the end of Mark Hamill's character. Force Ghosts have been around since back in Empire Strikes Back, when Obi-Wan appeared to Luke. The Last Jedi had an especially interesting Force Ghost, as a classic puppet version of Yoda spoke to Luke on Ach-To. Master Yoda's words ultimately help Luke find solace in his past, and together they destroy the ancient Jedi texts. While The Last Jedi has points of contention among fans, Yoda's appearance seems to be well received.
Logistically, it would also make sense for Luke to have a role in Episode IX, in the wake of Carrie Fisher's tragic death. The third film in this trilogy was set up to be a moment for Fisher to shine as General Leia. But her sudden death in December of 2016 threw a wrench into the writing process, and The Last Jedi ended up being her final appearance as her signature character. Episode IX now has the potential to be the first main installment without the trio of original heroes, and Luke's inclusion would no doubt be a comfort to the generations of fans out there.
With J.J. Abrams helming Episode IX, the man who brought the galaxy far, far away back will be able to complete the new trilogy of films. We'll just have to wait and see how it all turns out.