This was revealed by Reynolds himself during an interview with EW where he said, “I don’t know that there would be a Deadpool 3. I really don’t. I feel like the character, in order for him to function properly within his own universe, you need to take everything away from him. I don’t think that you can keep doing that.”
The good news is that Reynolds is speaking purely from a solo movie point of view, but he doesn’t rule out the possibility that the Deadpool character could return in a superhero mashup movie, like an X-Force movie, for example. “I do see him as being a part of X-Force, obviously. I would love to see him in a team-up sort of thing, like a mano a mano or a great female character from the X-Men universe.”
“I just think if you’re going to do another Deadpool solo film, you’ve got to really, like, get that budget down to nothing and just swing for the fences, and break all kinds of weird barriers, and do stuff that no one else can do.” It is unclear as to whether or not an X-Force movie will happen, but Disney did confirm that the X-Men, Fantastic Four, and Deadpool would be brought into the MCU once their acquisition of Fox is complete. In the meantime Deadpool 2 is set for a release on the 1st of June, 2018.