Re: 20th Century Fox upcoming Big Announcement
a simple option would be X4 after DOFP, as final movie with Full original cast, and two years later, go back to FC series and maybe keep going with them. along with other x-proyects, like new spin-offs.
Its not like Fox should do a whole new trilogy with original cast, but at least ONE movie, to give them one last time to shine, together.
Specially James Marsden, Cumming, Kelsey and Taylor. Thle ones that only have had one movie, appart from Cyclops, of course, but he is another story.
Next Big X-Men Crossover
* 2017- X-Men: Age of Apocalypse
Edit: Forget about 2017:
Official announcement -> X-MEN: APOCALYPSE - MAY 27, 2016!!!!