I think Fox will keep going with it.
The question is whether they risk a cross-over film. A cross-over could only help the F4, but it risks damaging X-Men which is currently very a successful and respected franchise.
I think F4 has missed the boat now. They could have worked as a foundation of the MCU, but that time has gone. I'm not really sure they work in standalone films (I'm sure the right people could give it a good try), and even an X-Men crossover doesn't seem very organic.
Marvel would love the villains - but how would you work the F4 into the MCU? Spider-Man can do it, he's a kid that is often off the radar. For F4 you would surely need an origin, and people are really bored of that. Maybe MCU could use them to kick off some 'Phase' in the future, but atm, meh.
Basically, I just don't see Fox having much to bargain with MCU. Marvel would like the villains, but they don't seem to focus on villains much anyway. This is maybe premature, maybe the film will do okay - but we could be looking at a cross-over, or another 10 year situation.