I feel as though a one off may be fine. But, I'm going to do a more insane proposition. I know these are not in their plans, but I propose a Sheild Triple Threat for the Universal Title at Wrestlemania. They had the Triple Threat at Battleground but if they change the dynamics up a bit, then it can be fresh.
Right now Seth and Dean are tag team champs and I hope they are for a good while. But, if there is a time to break them up, perhaps Royal Rumble time can be perfect where they lose the belts and argue after the match (maybe have a little tension in the build-up to the match) and in the Rumble match, one of them can eliminate the other, either accidentally, or on purpose. But, in the build up to Fast Lane, they can have qualifying matches for a number one contender's match for the Universal Title (held by Roman and I will explain how in a bit). Both of them are in separate matches. Dean wins earlier in the night, and in the main event, Seth Rollins wins.Then a team can try to attack Seth, and then Dean can come out for the save...with a chair. Then as the two are standing in the ring, Seth Rollins steps forward and Dean hits the chair on him, turning heel. Now we have babyface Seth and heel Dean, the total opposite of their feud post-Shield Break-Up and they're facing at Fast Lane where I propose Seth goes into the match hurt, and Dean cheats to win. Next week on Raw, when Seth is healed, he has one chance to earn his way into the Wrestlemania main event, and he does.
Next, how Roman Reigns becomes champ? Well, maybe have him beat Brock Lesnar at Survivor Series with help from Braun Strowman which can be done to build Brock vs Braun at mania because I'd want to see them in a Street Fight at Wrestlemania. Pure destruction. Now, here is a tricky situation with Roman, I know there are some fans of him on here, but he's kind of not really over still with a good portion of the audience. But, I'll admit, he's improved in the ring. Not to mention, it's odd for him character wise because he sees himself as a gray-area character, but he flip-flops from face to heel in my eyes. One second he is shaking Jason Jordan's hand, the next he's telling John Cena to fight him after he just had a match. A strong tweener character doesn't flip flop, they stay in a gray area. I say if you keep him a tweener character, then just have him be the middle ground in this Triple Threat.
Hopefully, this match will be a way to get the fans not to reject a Wrestlemania match with Roman Reigns in it.