#2 Ambrose turns heel

Well this is one of the most logical outcomes right now. The Lunatic Fringe turning on his brothers has been so heavily implied that everyone is expecting a Shield break-up due to Ambrose. The announcers are hinting at it, and that's one of the major reasons why this could really really come true.
It would make sense in a way. Rollins is the IC Champion, and the Universal title isn't going away from Reigns' shoulder anytime soon. This leaves Ambrose in a limbo. You can have your top star only for so long without a title. How are you supposed to root for someone who doesn't hold the gold or demand it?
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If Ambrose turns heel, he could feud with Rollins for his IC title, or move to the blue brand to reclaim the United States Championship.