#4 Cain Velasquez

Cain Velasquez has had a quiet few months in WWE after coming into the promotion with a bang. The former UFC fighter has wrestled in just one match in WWE, coming at last year's Crown Jewel pay-per-view in Saudi Arabia, where he was squashed by Brock Lesnar.
Velasquez hasn't been on WWE television since and there have not been any reports indication when he will return to the squared circle. His former opponent, Lesnar, will face off against Drew McIntyre at WrestleMania 36, putting his WWE Championship on the line.
Velasquez could perhaps interfere in that match, cause a distraction of sorts, to help McIntyre win his first-ever WWE Championship. This would help both Superstars in the match — McIntyre to get a run as WWE Champion, and ensure that Lesnar is still made to look strong.
This could also set-up a rematch between Velasquez and Lesnar further down the road, which should happen, considering how little action we saw between the two in their first meeting.