The X-Men franchise is a hot topic at the moment, but not really for what it's brought to the big screen, but what it could bring. The series has only managed to deliver on its potential a few times throughout the course of its six movie catalog (not counting spinoffs), especially when it involves the phoenix.
The powerful cosmic entity has been featured twice thus far in the X-Men films, but neither time has it been the central figure. The latest rumors from LRM sources say that the Dark Phoenix storyline could possibly be the focus of the next X-Film. It would be a logical progression from X-Men: Apocalypse, where Sophie Turners Jean Grey does access the Phoenix power within her, incinerating Apocalypse in the process. It would also give fans the real Dark Phoenix Saga they've been craving all this time, as the previous attempt did not live up to fan's expectations.
The thing is this seems to collide with previous sources that said the X-Films were getting reset to a degree, as Simon Kinberg has reportedly already started on a script for the next entry, and it isn't certain whether the stars of this current series of movies (Jennifer Lawrence, James McAvoy, Nicholas Hoult, and Michael Fassbender) will be returning.
Honestly, it's probably a mix of both. The series has built a nice foundation with the young group of mutants seen in Apocalypse, and could make them the stars of one or two more big films with a new director, as Bryan Singer is also reportedly stepping away from the franchise. If those are successful, you can always throw in some time travel to make the other stuff irrelevant. Of course, they could also hit the reset button completely and just bring back a few of the actors as a base for a new team, casting a new Wolverine, Xavier, and Magneto in the process.
Of course, the big dream is that FOX will work with Marvel on a shared universe sort of thing, but if that ever does happen, it's most likely a long way away.