I've always had a vision of how a possible Deadpool movie would end. He would narrate something to himself about how "his work was never done" and run away quickly. The next shot would be from in front of him, and he runs into the camera, which breaks and goes to black. In those last few moments before the credits begin rolling, Deadpool will exclaim "ow".
At some point he'd say "I can't believe Thor got his own movie before I did."
When it shows him without his mask he'd say "Yeah, I'm not pretty, but at least I'm not Ben Affleck."
A Deadpool movie, I think, would have to be based on Joe Kelly's original run. He's simply never been portrayed better, funnier, or had a more interesting storyline. The captive blind lady and the computer guy could be his supporting cast. The epic alien bringing peace to the world plot with the space law firm would be the overall storyline
Also, I think the only actor fit to play him would be Gary Busey.