Would love to see Taskmaster in Deadpool. But pretty sure Fox doesn't own the rights here, so very unlikely to ever happen.
If Fox was ever to make a deal to exchange characters I would hope it to be that one.
Edit: Just remembered Joe Carnahagn was going to do a Taskmaster movie, and I think that he said he was going to make it with Fox. So maybe I'm wrong. Other then that interview with Carnahaghn I don't think there's been any other info on where he resides. Would be very weird for Fox to own the character, but maybe they do.