#1. CM Punk

CM Punk has been "rumoured" for a WWE return for almost 5 years now. Even when there was absolutely no talk of his return, the dirt sheets seemingly felt as though WWE wanted him back too.
However, the cold, hard, bitter truth is that CM Punk has been gone for 5 years and has probably been the happiest he's felt in years. Nobody can blame him. If anyone had a job that they disliked severely, leaving it can result in some undiscovered freedom.
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Lately, CM Punk has been heavily rumoured to go to All Elite Wrestling, primarily due to his good relationship with the independent scene and The Young Bucks. However, he has publicly mocked these rumours and stated time and again that he won't be present at any AEW show in the near future.
With that said, Vince McMahon will definitely not allow Punk to return at RAW Reunion, even if he really wanted to.