Here’s the article from EW where Bryan Singer confirms that Jennifer Lawrence, James McAvoy, Michael Fassbender and Nicholas Hoult are all returning for the next X-Men movie.

We’re still weeks away from the unveiling of Fox’s ginormous X-Men: Days of Future Past (the cover of this week’s EW) but, fittingly, director Bryan Singer and producer/writer Simon Kinberg can only look ahead: The pair are developing, along with X2 writers Dan Harris and Michael Dougherty, the next X-Men film, Apocalypse, slated for May 27, 2016. Not much about the film is known, but Singer says that the film will be “somewhat” based on the 1990 comic storyline “Age of Apocalypse,” which features ancient villain Apocalypse and imagines an alternate universe. “[The movie] won’t necessarily create an alternate universe, but there may be some swapping things that I’m playing with,” admits Singer. Adds Kinberg, “From a visual standpoint it actually may be a bigger movie than Days of Future Past because there’ll be disaster movie imagery, like the title would imply.”

Days of Future Past will provide clues to the storyline of Apocalypse. Says Singer, “You won’t feel at the end of the movie that it set up Apocalypse. What it does is it sets up possibilities. But what we’ll discover in Apocalypse is that events in this movie made that happen.” He adds, “Apocalypse deals with ancient mutancy. What would humans have thought mutants were? What would mutants think humans were? You’re dealing with gods and things like that. And what if one survived and what if that found its way into our world?”
X-Men: Apocalypse will follow Charles (James McAvoy), Erik (Michael Fassbender), Mystique (Jennifer Lawrence), and Hank (Nicholas Hoult), and Singer says that those actors are all on board from deals signed for First Class. Singer also says he’s interested in bringing in other mutants, like Gambit and Nightcrawler. “I’m excited because I want to start introducing familiar characters at different ages and also explore the ‘80s.”