Cameos are the easiest thing for a future film to ignore, even if they weren't done for the sake of a 4th wall gag (and those appearances were done purely for a laugh, like a Family Guy cutaway scene). The film also had Deadpool go back and kill his fan hated incarnation from Origins, and Ryan Reynolds himself before he could film Green Lantern.
The only purpose of any if those scenes was to wink at the audience while getting so me laughter out of us, and for that they worked beautifully. But they aren't necessarily canon. If there is any recasting, and Deadpool comes across the new actor, expect him to reference the change in some way.
But it still won't make the Faux-Men MCU canon unless Feige says so - outside of the multiverse anyways. I'm sure they will have existed there.