Most people bring up the subject of Troy when asking this sort of question, and although it's not a sure thing I would imagine he'd do it. What about Chevy Chase though? Would he do it? Would they even be able to have him in a way that makes sense? He is dead in in the main timeline. He has tried to fake his death at least once before, but never successfully (unless you count the dark timeline.) I'm not sure about everyone else but I'd rather see the main timeline in the movie rather than one of the others, and I'm not sure if they could say Pierce is alive without it seeming shoehorned in. I curious to hear others thoughts though.