THR reports the script for Star Wars: Episode IX is getting a rewrite, and it is mentioned Rian Johnson's Star Wars: The Last Jedi script may need rewrites as well.
Colin Trevorrow is directing Star Wars: Episode IX and wrote the script with Derek Connolly. Now Jack Thorne, known for Julia Roberts and Jacob Tremblay's Wonder, is going to do a rewrite, though it is mentioned how extensive the rewrites will be is unclear.
Star Wars: The Last Jedi finished filming, so any rewrites would be for reshoots. The site mentions Star Wars: The Last Jedi "may also need script changes," so consider it currently unconfirmed.
The report also says Daisy Ridley, John Boyega, Adam Driver and Oscar Isaac are expected to return for Star Wars: Episode IX but seemingly teases character deaths as it's said "you never know who a Star Wars movie may kill off, so don’t get too comfortable."
News of Star Wars rewrites isn't unheard of as Star Wars: Rogue One underwent script rewrites as well as a directorial change in reshoots with Tony Gilroy. Most recently also saw the directors of the Han Solo movie fired with Ron Howard now on baord.
Star Wars: Episode IX looks to start filming in January 2018.