How is that possible, you ask? Hammil's Luke Skywalker died on-screen, while Fisher passed away in real life. Well, according to Abrams in a press release from Disney, Fisher's role will be comprised of unreleased footage shot for "The Force Awakens."
"We desperately loved Carrie Fisher," he said in the statement. "Finding a truly satisfying conclusion to the Skywalker saga without her eluded us. We were never going to recast, or use a CG character. With the support and blessing from her daughter, Billie [Lourd], we have found a way to honor Carrie's legacy and role as Leia in 'Episode IX' by using unseen footage we shot together in Episode VII."
There is no explanation as to how Luke Skywalker can return to the franchise, though fan speculation is that he would likely appear as a Force ghost, like other Jedi have done in the past. It's also possible, however unlikely, that Abrams will simply undo the death director Rian Johnson gave him in "Last Jedi," through some new twist.
Abrams co-wrote the screenplay for the film with Scott Terio. Filming is expected to begin Aug. 1, with Daisy Ridley, Adam Driver, John Boyega, Oscar Isaac, Lupita Nyong'o, Domhnall Gleeson, Kelly Marie Tran, Joonas Suotamo, and Billie Lourd returning from the previous film. They'll be joined by the aforementioned Williams, as well as Naomi Ackie and Richard E. Grant. And, of course, John Williams returns to score the final chapter of the saga he first joined more than 30 years ago.
The as-yet-untitled "Star Wars: Episode IX" is expected in theaters December 2019.