So far during the course of its production, 2016 "X-Men: Apocalypse" has been treated as the third and final installment in a second, prequel trilogy of X-Men films. The '80s-set mutant movie follows 2014's "X-Men: Days of Future Past" and 2011's "X-Men: First Class," which took the proto-X-Men on adventures throughout the '70s and '60s, respectively. With the decades-spanning trilogy wrapped up, it's been assumed that the current series' four main stars -- Michael Fassbender, James McAvoy, Jennifer Lawrence and Nicholas Hoult -- would say goodbye to the franchise as well. A new rumor, though, calls that line of thinking into question.

Heroic Hollywood has heard from an unnamed source that, over the weekend while Channing Tatum was firming up his deal to star in "Gambit," a pair of other mutant actors also finalized a deal. According to the rumor, Michael Fassbender and James McAvoy have agreed to stay on as Magneto and Professor X for an unspecified amount of further X-Men films. Fox, Fassbender and McAvoy have not commented on this rumor yet.

The other two stars, Lawrence and Hoult, are not included in the rumor and the pair of actors have been vocal about the odds of them returning. When asked if she's consider playing Mystique again, Lawrence told Yahoo! that she would literally go with her gut when asked.

"I'm finishing out my contract, yeah," said Lawrence. "I told Fox not to not ask me." Fassbender then joked that Lawrence wants to have the option to turn them down. Lawrence played along, saying, "I kind of want to bait them with a text and then when they call me, I go, 'Don't call me!' and then hang up. I don't know -- I love doing these movies."

Hoult also opened up about the possibility of returning as Beast during a talk with E! Online. "This is the last one I'm signed up for," said Hoult, who noted that that didn't necessarily mean it would be his last one. "The first one did so well and ['Days of Future Past'] got received so brilliantly, it's like, 'Wow, people really want to see the films' and the best thing is it's a great crew and cast to work with and he's a fun character. I have a good time playing him so I'd keep making them."

"X-Men: Apocalypse" -- which may or may not be the final film for Fassbender, McAvoy, Lawrence and Hoult -- opens on May 27, 2016.