I was wondering the same thing myself. Two key points to keep in mind are A) There's no way that FOX is going to put out a quality FF film for $120 million, and B) An FF reboot has zero chance of outgrossing a Jackman-led, Asian based Wolverine film.
If FOX is concerned that audiences were turned off by XMO:W, how will they respond to a reboot of the horrific prior two FF films, especially considering that a large % of comic book movie fans are hoping the film is never made? And this time around FOX is losing merchandise revenue - Disney/Marvel isn't going to move Avengers related product off of the shelves to make way for Thing hands and feet. Unless FOX is willing to waste $150 million or so to poke Disney/Marvel in the eye, I can't see a reason for them to greenlight this film.