#2. Seth Rollins
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Seth Rollins' resurgence as a heel hasn't been as big a deal as many had hoped. Perhaps his 2014-2015 run as WWE's top heel was too high a standard to set since he was carrying the company on his back for over half a year before getting injured.
Either way, he's always going to be one of WWE's most prominently pushed Superstars and rightfully so. He's established himself on a level above most and while he may not be competing for any World title right now, it's only a matter of time before he does.
Although Goldberg vs Seth Rollins isn't a match that may have crossed many minds, the fact that it puts a top RAW star against a legend like Goldberg is big enough to sell itself as a PPV main event.
Seth Rollins has achieved almost everything there is to in WWE minus a full-fledged WrestleMania main event (though he technically headlined WrestleMania 31).
Either way, he wouldn't be the worst option to pick for WWE to retire Goldberg when the time comes.