Undertaker has creative control over his streak so it's choice when it ends or not.
Look at the other people he was willing to give it to. Kane at WM14, Orton at WM21, Angle at WM22 (supposedly, I think.) He had never faced these people before at Wrestlemania so it would have made sense if he lost to any of them. Kane would have made sense since they could have continued to push him as an undefeated monster. I was glad as hell when Orton lost, but objectively, it would have made sense since Orton was young and had most of his career in front of him, not to mention he was the "Legend Killer." Angle makes the least sense since he was already established enough as a wrestler by 2006 that I don't think he should have been given the streak, but at least he and Taker had never faced before at WM.
With Triple H, however, he's very much an established veteran, and would gain nothing from it. Not to mention he's already lost twice to Taker already. And he's semi-retired as it is.
The best bet is a young guy in the position that Orton was in at WM21. Someone who is young and has most of their whole career ahead of them but who also isn't a complete rookie. This is the only way Taker losing could mean anything in the long run.
But I agree with those who don't think Taker should ever lose the streak. It's a huge part of his legacy and I think at this point, he has won so many times that it would almost be a waste to end the streak now.
