Re: Where does the franchise go after this?
It seems the more easy approach would be to keep the FC third part for a future year, and focus on the original cast at least on one final sequel or two, in case the studio wants to play big.
The FC cast can age a bit, so once they shot the third part the writer and director can jump to the 70s and the actors look would be more realistic, without the need of makeup to ALL the cast, lol. The more they wait for this third part, the biggest Jennifer and Michael Fassbender will be, so the hype would be pretty nice too.
Its a similar scenario to a possible X4. Since its been so many years, the hype to have them on screen again is cool, so they can play this card with both casts perfectly.
Next Big X-Men Crossover
* 2017- X-Men: Age of Apocalypse
Edit: Forget about 2017:
Official announcement -> X-MEN: APOCALYPSE - MAY 27, 2016!!!!