Well, strictly speaking they’ve just signed [Josh] Brolin to play Cable in Deadpool 2, and he’s got a four picture deal accordingly. If the Deadpool series starts tanking then that’s that. On the other hand… since Deadpool is pretty much the only non-MCU, but Marvel-derived project that isn’t collapsing under the weight of its own suckitude*, there’s a pretty good chance that Brolin’s going to be wearing that costume in a bunch of movies. Assuming that Deadpool doesn’t go running for the MCU.
Which they may not want to do. The MCU is owned by the Mouse, after all. The deal that would be have to be made to get Deadpool working with Disney is kind of frightening to contemplate.
UPDATE: I was distracted by the smell of tasty, tasty chicken-under-a-brick. As Constant Reader Canthros in comments noted: Josh, not James.
*Spider-Man no longer counts. Unless Homecoming sucks. Please, God, don’t let it suck.