#3 Dean Ambrose
Dean Ambrose returned to the WWE after a nine-month long break. The Lunatic Fringe returned on August 13, 2018, to help his Shield brother Seth Rollins against Dolph Ziggler and Drew McIntyre.
Dean Ambrose walked out on the Shield past week on Raw, hinting towards a heel turn. This could perfectly create a feud between Reigns and Ambrose. Ambrose has always been supported by his fans, and if he turns on Reigns, the fans are likely to support the Lunatic Fringe.
There have been some speculations that Vince McMahon wants to do a triple threat match between the members of The Shield at Wrestlemania 35 for the Universal Championship.
It would be great to see Reigns and Ambrose fight each other for the gold, Dean Ambrose winning the championship from Roman Reigns can set up the feud between them and lead to a match between the Shield brothers.