#4 Baron Corbin

The Constable of Monday Night RAW may be an unlikely choice, but it could make sense. Corbin is supposed to be the hand-picked spokesperson for WWE RAW Commissioner, Stephanie McMahon.
McMahon, like her husband and her father, have had on-screen issues with Roman--what with Reigns having memorably feuded with The Authority over the years.
How Brock Lesnar ruined another wrestler's career - Watch Now!
As Steph's representative, Corbin could curry favor with the boss and book himself in the match, which certainly would lead to some interesting confrontations between The Constable, the Big Dog, and the RAW General Manager, Kurt Angle.
Granted that this may be yet another Reigns vs. Authority angle, however, the inclusion of Corbin into the equation would, beyond the shadow of a doubt, add a new layer of intrigue to this potential storyline.
A top WWE star is missing in action