Personally I think they'll make another X-men movie (reboot) before doing X-force. It's the much stronger brand, and it would make more sense to spin off X-force from X-men. So my guess is if Fox does hold onto the license they will relaunch X-men first, either with this new cast of younger actors or they might recast it altogether if they are looking to bring in a new director that has an all new vision for the franchise. We know Jackman will be hanging up the claws so it's likely that actor they cast to play Wolverine will be the anchor (not the leader) for the new X-men team, and will also probably lead the covert, edgier X-force which is why the spinoff would make sense after X-Men. Also Jen Lawrence won't be coming back as Mystique, it won't surprise me to see Fassbender out as well because he's in high demand. And if that happens is McAvoy going to want to continue shaving his head to play Prof X, especially if he is no longer in a cast with A-list actors of Academy Award winners? So that could mean a recast. But who knows what Fox might offer Fassbender and McAvoy to stay on if the movie is a big hit. It's still possible all or most of the young actors might return for the reboot since they won't command high salaries and will be somewhat established. And that is provided Fox doesn't sell the license back for a big chunk of cash, or do a share deal like Sony, which still wouldn't surprise me.