X-Men: First Class was set in the '60s while X-Men: Days of Future Past was partially set in the '70s. X-Men: Apocalypse is set in the '80s and the that film's follow up will be set in the '90s. The news was confirmed by executive producer Simon Kinberg during a press conference for the film's premiere.
Who do you want to see the X-Men face next? After the Hellfire Club, Sentinels and Apocalypse, it's hard to imagine Fox utilizing someone other than Mr. Sinister or Onslaught. Perhaps Fox will break traditon and provide a hint in Apocalypse?
Since the dawn of civilization, he was worshipped as a god. Apocalypse, the first and most powerful mutant from Marvel's X-Men universe, amassed the powers of many other mutants, becoming immortal and invincible. Upon awakening after thousands of years, he is disillusioned with the world as he finds it and recruits a team of powerful mutants, including a disheartened Magneto (Michael Fassbender), to cleanse mankind and create a new world order, over which he will reign. As the fate of the Earth hangs in the balance, Raven (Jennifer Lawrence) with the help of Professor X (James McAvoy) must lead a team of young X-Men to stop their greatest nemesis and save mankind from complete destruction.