Karen Gillan has confirmed in an interview with Yahoo! Eterntainment that Guardians of the Galaxy 3 script has been completed and that it's "wonterful".
“I can say that I’ve read it and it’s amazing,” Gillan hinted. “We’re all really excited that James is back to complete the trilogy because it wouldn’t have felt right without him. It’s a wonderful, wonderful script.”
Gillan also said that she didnt read the entire script of Avengers: Endgame even though she's one of the major players in the film.
“I didn’t get the whole script,” she revealed, “but I got a good chunk of it and so I could easily work out what was happening.When I signed on to Nebula, it was eight days of filming and she was supposed to die in the first Guardians film,” she explained. “So to go on and be able to evolve the character and then have her be this pivotal role in Endgame was amazing. I didn’t see it coming at all.”
James Gunn is now working on the reboot of The Suicide Squad, so Guardians of the Galaxy 3 release dates are still unknown.