I dunno if the kids would be that sad, even if Cena cheated. I think he'd have to do something more despicable to get a full blown heat, something like Hogan and the nWo, cheating to break the streak wont cut it. Austin sided with McMahon to cheat the Rock @ the greatest WM ever and that was probably the WWE equivalent of Hogan-nWo and the crowd was bipartisan at best.
If they did it in an anti-Cena city up north like New York or Philly, then maybe, but not in Phoenix. Cena's gonna have to beat the shit out of Bret in that match then really really cheat Taker, like knocking him unconscious with a chair or something than making him "submit" ala Stone Cold passing out @ 13.
If I had it my way, Cena still turns heel, but loses to Taker and give Taker plenty of time off to be ready to end the streak @ 27 to a really built up Miz. Give Miz a nice, slow build, win MITB, throw in a title reign, and he's ready. I can't think of anyone who would be more perfect for it if they play Miz's cards right this upcoming year.