Though the plan appeared to be Brock Lesnar vs. Roman Reigns a few weeks ago, WWE may have decided to switch things up and could make the SummerSlam main event a 4-way match between Lesnar, Reigns, Braun Strowman and Samoa Joe, according to Dave Meltzer in the Wrestling Observer Newsletter. Based on the end of the Reigns vs. Joe match on Raw, with Strowman attacking both men, it would appear that that’s where WWE may be headed. They could also obviously just do Reigns vs. Lesnar and Joe vs. Strowman as two separate matches, but it seems like Strowman and Reigns still have “unfinished business.”
The plan still appears to be that Roman Reigns will win the Universal Championship at WrestleMania, so Meltzer speculates that if they are going to have Lesnar drop it now, it would seem to make more sense for either Strowman or Joe to win the title at SummerSlam (if they do end up doing a 4-way match) rather than having Reigns win now.
Another thing to note is that if Brock Lesnar does end up leaving WWE (his contract expires right after WrestleMania), Meltzer speculates that fans could turn on him. This could end up actually getting fans to cheer a Roman Reigns win at WrestleMania, though it would also make the match insanely predictable if everyone knows Lesnar is leaving, so I’m not sure that a super-expected Reigns title victory would be received that well.