According to WrestleVotes, this year's Royal Rumble winner will be someone who won in the past and that definitely narrows down the possibilities. The most likely candidates have to be Triple H, Randy Orton, John Cena, Shinsuke Nakamura, Batista, The Undertaker, Rey Mysterio, Sheamus, and, sigh, Roman Reigns. Could the Big Dog end up headlining yet another WrestleMania? Probably.
Either way, WWE's plans will start becoming clearer in the coming months and we know that the company's plans frequently change so it's possible that a totally new winner will end up being chosen.
It seems like a shame that someone who has won before will win again as it's always more fun when a newer Superstar manages to emerge victorious in the match for a chance to become WWE Champion at Wrestlemania. Someone like Rusev or Andrade "Cien" Almas would obviously be a lot more exciting than the likes of Orton or part-timer Superstars like Triple H or The Undertaker.