They director implied that Cable will be appearing in Deadpool 2. Or at least stated that they HAVE to include Cable otherwise the fans will crucify them.
If that's true, I wonder if we could be building to an X-Force movie (I know there's been rumors that X-Force is one of the projects coming down the pipe); We have Wade, Psylocke, Archangel, and you could go Warpath, which means Cable would be the only missing piece aside from a possible recast Wolverine with Jackman retiring from the franchise (although I'd rather they introduce X-23 to the films, especially since she's going to be the new Wolverine in the books once the Secret Wars nonsense is over).