In terms of non-main-roster surprise entrants, it’s hard for me to imagine a bigger pop than if WALTER were to appear. Send him in early, have him clear out some stiffs, then introduce Braun Strowman for the This Will Be At Wrestlemania
The problem is that they put him on Survivor Series and jobbed him out already because Vince apparently isn't a fan. So that idea seems like a bit of a stretch. Besides, WALTER is better off as a big fish in a series of small ponds where he can do what he wants, when he wants.