#4 Samoa Joe
This one depends on whether Samoa Joe returns from injury in time. Last year at WrestleMania 33, almost every single member of the male roster from Raw and Smackdown competed on the card in some form or another, in part thanks to the annual Andre The Giant Memorial Battle Royal. Conspicuous in his absence from the whole event (pre-show included) was Samoa Joe, who had only recently graduated to the main roster from NXT.
Many expected the 'Samoan Submission Machine' to interfere in Seth Rollins's match that night, against Triple H. The reason being that Joe had served as The Game's enforcer leading up to that event, taking out Rollins several times on Raw in the run-up. However, Samoa Joe was nowhere to be found that night.
Joe will be 39 years old by the time 'Mania rolls around. He's not got many WrestleMania moments in him at this stage of his career and as a world-traveller, he deserves a spotlight on the grand stage. A storyline with Seth Rollins is one that writes itself by drawing upon how Samoa Joe nearly cost 'The Architect' another WrestleMania last year. In addition, Joe's most recent feud before being sidelined was against The Shield. Roman Reigns will likely be busy with the 'Beast' at Wrestlemania, while Dean Ambrose is out with an injury of his own. That leaves Seth to fend off 'The Destroyer'.