The following contains MAJOR SPOILERS for Star Wars: The Last Jedi. Do not read until you've seen the movie.
Now that Star Wars: The Last Jedi is a real thing that many of us have now seen, we're already wondering what's next in Star Wars: Episode IX. Episode VIII took many risky steps in its story which leaves the future open for many of the film's characters. However, for one character, Luke Skywalker, the future appears to be closed off. Of course, that's only the case from a certain point of view. From another perspective, Luke's story may not be quite over.
Star Wars: The Last Jedi ended with a climactic battle between student and teacher as Kylo Ren faced off against Luke Skywalker. However, it turns out that the battle wasn't quite what we were led to believe, as Luke was never actually there. Instead, he used the Force to project an image of himself across the stars. He left a parting shot to his former student ("See you around, kid") before vanishing from Crait. However, Luke struggled when it was all over. Exactly why isn't totally clear, but it seems the effort just took a lot out of him. It appeared at first that Luke was able to regain himself, but shortly thereafter, he vanished entirely.
There are multiple potential explanations for Luke Skywalker disappearing, but the most likely is the same reason that we've seen other Jedi like Yoda and Obi-Wan Kenobi disappear: they died. Of course, in the two previous cases, we saw those characters again, and so it stands to reason that even if Luke Skywalker is dead, we haven't necessarily seen the last of him. Star Wars: The Last Jedi even brought Yoda back, in case we'd forgotten what was possible.
Especially considering that the other two original trilogy heroes will not be returning, it seems highly unlikely that we won't see any of the big three in Star Wars: Episode IX. Luke Skywalker is the only one who can, and there's a perfectly legitimate "Star Wars reason" for him to do so. It won't be a major role or anything, or at least it shouldn't be, but as long as Luke says something, he'll have a more significant impact than he did in Star Wars: The Force Awakens.
What's more, it makes sense to see Luke again. He does, after all, tell Ben Solo that he'll see him around. He doesn't sound like he's just talking. He sounds like he means it. When Rey speaks with Leia at the end about Luke being gone, she says she felt "peace and purpose" when she felt him fade away. Part of that purpose was surely to act as an inspiration to others, as we see the story of what Luke did filtering back to other parts of space as the film concludes. However, what's not clear is if anybody else actually realizes Luke is gone. Nobody was there to see him die, so this wasn't a heroic sacrificial moment. If Luke's death was an accidental side effect of his efforts, he might have felt peace upon death, having accomplished his goal. Feeling purpose implies that Luke's fading away to become one with the Force is part of a means to an end. He has a goal. Perhaps, we'll see that goal come to fruition at the end of the trilogy.
SPOILERS: Star Wars: The Last Jedi Ending - What Happens And What It Means
Hopefully, Star Wars: Episode IX will give Luke Skywalker one last opportunity to make an impact on the galaxy. Whether that's simply to act as an inspiration to Rey or to impart some great wisdom that will aid her, I'm guessing we haven't said goodbye to the Skywalker family quite yet.