Re: Who would you be okay with endng Undertakers Streak?
At this point, there's really no one. I'm not all that excited for the prospect of a Punk/Undertaker rematch, but if there was one, Punk should win. He's a safe bet for WWE (not as injury prone, stays within boundaries even when pushing them, relatively young, proven to be over, etc.)
Ambrose is still too early in his career, but they could do Taker/Ambrose if they wanted at WrestleMania. Still, when a wrestler hasn't been "broken in" or "paid his dues," it's a huge risk to give him such a big win when he'd only have been in WWE for 1.5 years by WrestleMania XXX.
I guess I'd be okay with Brock winning it. He's got people's respect and would be a believable threat.
Cena winning would be a bit much on top of beating The Rock and being an 11-time WWE Champion. He has the credibility to do it and definitely poses a threat, but shouldn't win. Especially with people already booing him... unless they turned him heel.
Personally, in my fantasy booking world, I think it should be Taker/Cena at WMXXX, Title vs Streak, with Taker winning and retiring as Champ. It sets up a tournament to help with the post-WrestleMania lull (similar to what we're experiencing now), gives Taker his ultimate due, and preserves The Streak, which is really a WWE institution at this point.