#4 Dean Ambrose
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Dean Ambrose is a bit of a wild-card here. The former Shield man has been off our TV's since the end of last year, and fans are beginning to get super excited for his presumably imminent return.
Ambrose has not been in the title picture since later 2016, but a surprising return always supplies a wrestler with a wave of momentum, and if he comes back as a heel, as many fans suspect, then the WWE could just decide to put someone fresh into the title picture.
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It seems unlikely, largely because Lesnar and Ambrose have worked together in the past, and Ambrose was fairly vocal about Lesnar's work ethic following what was a very disappointing encounter.
A feud with Roman Reigns or Seth Rollins seems more likely for Ambrose when he does finally return to the ring.