According to FirstShowing.net on Dec. 6, the end tease of "X-Men: Days of Future Past" reveals an encounter Magneto has with Apocalypse. Inside sources who had access to the script had been able to give some tidbits of what is to become the future of the "X-Men" movies.
The end credits tease shows Magneto hunkered down in a run-of-the-mill shack and is apparently a fugitive from authorities that are on the hunt for him.
As he makes way to draw water from a well, he sees something fall from the night sky. As he goes to investigates the impact zone, a large being emerges from the wreckage. The massive, towering, and terrifying being with a twisted metal face and pits for eyes says his first words to Erik. The exchange in verbiage is pretty short.
"I have crossed rivers of time to find you".
Magneto asks, "Who are you?" and then Apocalypse responds, "I am your future".
After such a brief exchange, Apocalypse merges with Magneto and all of a sudden a serious blast eminates from Magento leveling everything for miles. The possessed version of himself then realizes the amount of damage he is now capable of and gives an evil grin.
At that point, the film cuts to black and this looks like it could indicate the cast from "X-Men: First Class" could return in the sequel following "X-Men: Days of Future Past". For those who are not familiar with the Apocalypse character, fans may want to familiarize themselves by engaging in the "Age of Apocalypse" story arc which also involves some kind of time travel. After all, Apocalypse has "crossed rivers of time" to find Magneto and there seems to be some similarities to the written comic.
So it looks as if the future time line that will be prevalent in Bryan Singer's upcoming sequel may also transpire in the "X-Men: Apocalypse". According to sources, even the "X-Men: Days of Future Past" cast of characters should be returning.
The only issue that may be concerning that these time travel story lines could be confusing to the non-fan, but hopefully by that time they could evolve into fans if they stay faithful to watching the films in their appropriate order. Perhaps this will prompt those who aren't quite well studied in the comic book world to go out and read the story arcs that will allow them to comprehend what's about to happen in the Marvel Cinematic Universe.
Also, keep in mind, just because they are merging together as one doesn't mean they'll be becoming allies. As the story arc indicates, they are opposing forces. It would also make sense that only one mutant villain could only rule mutant kind with complete satisfaction.
"X-Men: Days of Future Past" is scheduled to be released on May 23, 2014.