#3 Have Bobby Lashley injure him
Bobby Lashley needs to make a statement to cement his new heel turn. With that being said and going along with WWE using Balor as the fall guy to build talent up, why not have Lashley outright injure Balor during a match. Of course, this would write Balor off of television for a while, but it also builds a lot of sympathy for him in the process.
WWE is already teasing a match between the two, especially after Lio Rush's constant taunts towards The Demon King, which would be the perfect time to pull something like that off. At the end of the day, it doesn't matter how WWE does this, it just needs to make Lashley look cruel and make Balor look sympathetic
Once some time has passed, WWE then brings him back and have him confront Lashley which sets up a feud between the two. Balor then could get his heat back with a huge win over Lashley at the next pay per view and then give Lashley a win further down the line to become number one contender for The Universal title.