#2 Adding someone to the match
Let's be honest here - Brock Lesnar versus Roman Reigns on its own is not going to be a WrestleMania worthy main event. Of course, people are going to think that it has to do with the immense amount of dislike the former Shield member garners on a weekly basis, but it is also due to the fact that WWE has already done this before.
In fact, WWE tried to do this same match at WrestleMania 31 as a way to cement Reigns as a future WWE Hall of Famer, but they ended up having to abandon that outcome after the fans didn't receive Reigns well leading up to the match. Interestingly enough, WWE were then forced to turn it into an impromptu triple threat after Rollins decided to cash in on Lesnar and Reigns.
A top AEW star just called one of his colleagues 'spoiled' and 'narcissistic' HERE.
With that being said, it should pretty obvious that WWE would greatly benefit from a adding a third man to match at WrestleMania. Not only does doing so give Lesnar the chance to keep his undefeated streak going, it also allows WWE to build up a young underdog in order to garner more interest for the match.
In the end, WWE really needs to consider a plan B here, and it would be wise to put someone like Braun Strowman, The Miz, Finn Balor, or even Seth Rolins into the Universal title picture at WrestleMania 34. If not, they risk upsetting fans at this year's show of shows, and even further hurting Reigns in the long run if they do decide to give him the title.