For the last five yeas, Roman Reigns has been pegged to lead WWE in the Hulk Hogan/John Cena role of top babyface. While his fan reactions were usually mixed to negative, he was more or less "the guy" do to the intensity of said reactions, and WWE's insistent push. The company was operating under the assumption that he would be occupying the role or at least the next five years, plenty of time to find a new top face in the process.
Obviously, their plans have now hit a snag. Look, we have no idea what kind of leukemia Roman Reigns has right now, but no kind is to be taken lightly. It could be months before we see him again, it could be several years, it could be never, we just don't know right now, and something tells me WWE doesn't either.
With that said, there's still shows to be put on every week. There's still the matter of SmackDown moving to FOX next fall. Someone has to step up to the plate and be promoted as "the guy" until Reigns can come back, or take the role permanently if he's not able to.
Thankfully, it's not as though WWE are hurting for candidates. While some (Styles, Nakamura) are too old, while others (Strowman) are too one-dimensional, there are plenty of young guys with good looks and great athleticism that, we think, would fill the role of top guy perfectly.