Not only was Days of Future Past a good X-Men film (an occurrence that's rarer than we'd like), but the film set the franchise off on a new course, basically pulling the best parts from the series' messy timelines into one cohesive story line. However, this tampering with history will have effects beyond just simplifying the X-Men film canon.
It's expected that X-Men: Apocalypse's titular villain will come on the scene as a direct result of Days of Future Past's timeline reset; something that film's button scene already hinted at. On top of that, Apocalypse will undoubtedly be the X-Men's greatest foe to date, and doing battle with this titanic threat will make X-Men: Apocalypse the largest, most massive X-Men film yet.
Along with the film's more massive scope, the cast too is expected to be larger. Yesterday, Singer shared a photo on his Instagram account announcing that the casting process for Apocalypse had begun, and that presumably all these empty chairs will soon be filled with the next class of mutants:
The glamorous casting process begins! #XmenApocalypse
For this installment we already know the core cast from X-Men: First Class will return and that it will again jump forward another decade, this time to the 1980s. And thanks to how neatly Days of Future Past brought together the two generation of mutants, many are expecting younger versions of that later X-Men team to appear alongside First Class' veterans. Perhaps one of those seats above will be filled by a young actor or actress playing Storm, Jean Grey or Cyclops?
There's a good chance we'll see Quicksilver return, considering how well fans responded to that character's role in Days of Future Past. Singer has also mentioned his keen interest in bringing fan-favorite characters like Gambit or Nightcrawler into Apocalypse. And since Fox has already gone through the trouble of casting Channing Tatum as Gambit, it only stands to reason he'd eventually show up in an X-Men film.
It's also safe to assume there'll be a few new mutants joining in on the fun in Apocalypse. At the moment the frontrunners are Psylocke and Cable, and since both are characters who made their comic book debut in the 1980s, they'd be a good fit for this film's setting. Cable even more so, seeing as he's the time-traveling son of Cyclops and often teams up with another of Fox's Marvel characters, Deadpool (who is finally getting his own flick in 2016).
What characters - new and old - are you expecting to show up in X-Men: Apocalypse? Do you have any actors in mind for younger versions of already established mutants? Let us hear from you in the comments below!