Originally Posted by psylockolussus
With the FF reboot being development right now, I don't see why it would be impossible.
Its not like they are integrating the FF world featuring Jessica Alba and the actors we saw in FF/FFROTSS into the world of the X-Men. The world of Fantastic Four hasn't been established yet since its being rebooted right now.
The thing is that I don't trust Fox with properly merging X-Men and the FF together.