#4 Rusev
Rusev may be one of the unlikeliest Superstars to possibly face Roman Reigns in this list, but WWE could pull off a surprise by having him face The Big Dog.
Rusev, much like his partner Shinsuke Nakamura, has been severely underused on SmackDown Live over the past few months. And there have also been reports that Rusev may quit the WWE, with reports linking him with a switch to AEW.
WWE may perhaps put him in a program with Reigns for a little while to keep him happy and in the company, as he clearly has the talent, and his Rusev Day gimmick showed that the WWE Universe like him too.
But, a feud between Reigns and Rusev will not help either Superstar. Rusev and Nakamura must go after the SmackDown Tag Team titles as they are one of the most talented heel tag teams on the blue brand. For the duo to get back to the top of the card, they have to work from the bottom, before getting a shot at the likes of Reigns.
This feud has also happened before on RAW and we aren't sure if we want to see it again.