I heard that Lesnar is the front runner to fight Taker at Mania. It would make sense story wise. Heyman betrays Punk cause he wasn't good enough to beat Taker, proves Lesnar is superior to Punk, then brings his superior client to Mania to try and finish what he started the previous year.
If it's gonna be Taker's last mania I think I'd rather see him do one more match with Kane to finish both of their careers. Kane is pretty much a midcard guy these days and doesn't have the credibility to end the streak but who really thinks they will end it anyway? A lot people think they're gonna reveal that Kane was indoctrinated by the Wyatts so maybe they can come up with something revolving around that.