I just said -- let Marvel handle the creative side. Fox would still produce and profit from the FF films, but they would now be part of the Marvel Cinematic Universe and benefit from its box-office cachet, and from the seemingly do-no-wrong creative approach of Marvel Studios. Exactly like what's already happening with Spider-Man.
I'd say the difference is that some of the five Spidey films were actually good (I'd say two of them, others would say three) so people will give them another chance. F4 films have been crap all the way down.