Taker beats Lesnar clean at Wrestlemania 30.
The following night on Raw, Taker cuts a promo teasing retirement. He has beaten everyone there is to beat in the industry. Just as he starts to wonder aloud if the time has come to hang 'em up, a shitty instrumental WWE version of "For Whom The Bell Tolls" fires up over the PA system. Out comes Sting.
Much like how Cena and Rock set the date a year out for a Wrestlemania main event the night after Mania, Taker and Sting will do the same, setting up a "legitimate contender" for the streak.
This gives Sting a year to ensure he is in wrestling shape, and gives both of them a full year to brainstorm on the match. Let's face it: Sting loses credibility as a possible threat to the streak with every passing year. Neither of them are getting any younger. If the E is going to pull the trigger on the matchup EVER, they have to do it next year.
With Taker beating Sting at Mania 31, this doesn't leave many contenders to the throne. My guess is they give Cena a shot at the streak. My guess is that Cena will be the 25th man in the 25-0 streak that they will probably reach before Taker retires. I would love to see them build someone else up to contend in the meantime. My best guess: Cesaro and/or Reigns will be suitable opponents. Only time will tell.