Deadpool 2 is definitely going to be the set up for the X-Force movie. It makes sense, given that the film will include Cable, Deadpool, and Domino, all members of the team. Here’s what the writers, Rhett Reese and Paul Wernick, had to say:
RHETT REESE: There is a responsibility we have to the X-Force universe, and I do think we will not disappoint the fans going into Deadpool 2 and then setting up X-Force and beyond.
PAUL WERNICK: We never want to let the tail wag the dog. We want to tell the best Deadpool story we can. But I do think we have a responsibility to think about a larger universe in the way that Marvel does and start to put pieces in place. Some of these movies feel overstuffed and almost choking with the need to set up eighteen different things that pay off down the road, and we want to avoid that responsibility to the extent that it hurts us. We want to hint at things, we want to plan some characters, and we want to make some nods, but we’re very, very cognizant about making sure that Deadpool is above all a Deadpool movie.
REESE: Its purpose is not to set up X-Force. It will likely set up X-Force, but the drive of the movie won’t be our eyes on Movie 3.