Star Wars: The Rise of Skywalker was intended as something of a love letter to the history of the saga, and one way that this factored into the plot was in the presence of Force Ghosts – or, at least, Force Voices. During her climactic fight with her evil grandpappy Palpatine, Rey was spoken to by the spirits of many Jedi who had gone before her – everyone from Anakin Skywalker to Ahsoka Tano.
This subtly upturns previously established facts about how Force Ghosts work, though. In the old EU/now Legends stories, a Jedi could only become a Force Ghost for a brief period of time before passing over into another plane of existence. The voices Rey heard seem to confirm this is not the case in modern canon, however. The Rise novelization confirms this and goes even further, revealing that Leia received messages from Obi-Wan and Yoda which helped her learn about the Force.
This is a pretty big deal, as it confirms that Force Ghosts can act as mentors to the next generation of Jedi. ScreenRant has suggested that this could even prove key to the renewed Jedi Order that Rey will no doubt set up following the events of Episode IX.
Remember, Luke and Leia’s ghosts are with Rey in the movie’s final scene, when she buries their lightsabers on Tatooine. What if the Skywalker twins remain by Rey’s side and aid her in training up other Force-sensitives from around the galaxy – like Finn (possibly) and that kid with the broom from The Last Jedi?
Obviously, Leia’s character will likely be rested out of respect for Carrie Fisher, but this leaves the door open for Mark Hamill, at least, to return in some kind of follow-up film based around Rey. There may well be one already in the works, too. Like Luke says in Star Wars: The Rise of Skywalker, a thousand generations of Jedi live in Rey now. But it would probably be helpful if some of them could lend a hand with the teaching.