A few years ago I was an advocate of using the streak to make a new star, and had it been done earlier on then that might have worked. However WWE have built it into such a big deal that I think if it ends then it's used to create the greatest Mania moment since Hogan vs Andre, not to give a guy with a year or two in the business the rub.
As The Batman says you could well throw it away as you don't know who will last, and on top of that I think it could be more of a curse than a blessing, fans are unpredictable and they may well resent some new comer beating an icon, the win could become a millstone around that guys neck.
Edge could have been the guy that straddled both options, he was a main event guy and multi-time Champion, but ending the streak would have taken him to a new level, however he would have been finished 3 years later. Some made the same argument for Batista the year before but listen to the crowd during that match, they did not want Batista to be the guy, he simply was never over enough, just like Sheamus isn't and never will be.
I think the crowd would have accepted Punk ending it but it wasn't the right circumstances for that to happen, and I think if HBK had ended it at Mania 25 the fans would have loved it as in many ways Shawn deserved that moment. At this point I think and feel that it should be Cena, or nobody.