#2 Vince McMahon

This one shouldn't be ruled out. While Vince is certainly far too old to be competing in any major matches, the WWE owner has never been one to shy away from the limelight, and certainly not from a big Wrestlemania match.
Vince has legitimate reasons to want revenge on Zayn and Owens, and it does seem awfully coincidental that Shane referenced Owens' assault on his father for the first time in months this week, especially with the Chairman returning to WWE television on Raw this past week.
Did you know a top WWE Superstar just wrestled outside the company? More details HERE
This match would have a novelty factor, as it has been a very long time since we saw Vince McMahon step foot inside a WWE ring as a performer, but there is no chance (in hell!) that this would be a good match-up.
Shane would likely have to take some major bumps, and there is no way that anyone would buy Shane and Vince picking up a victory over Kevin Owens and Sami Zayn.