To be honest, I wouldn't be keen on this idea. WWE has never and probably will never let Punk go over Cena absolutely clean. If they have this match, Cena will either win or lose controversially, which would suck. Plus, even though it was all dirty wins, I swear I've seen Punk beat Cena a good 30 times off of some shabby excuse, and to give him the clean win would just kinda clarify what we already know. I personally don't think it would be smart knowing WWE's extremely hit or miss booking with Punk and their Stevie-Wonder-throwing-ninja-stars misses in booking Cena. If their gonna give Punk the Ironman match, give it to someone he has history with, can put on a good match with and can reasonably (within kayfabe booking) trade wins with, like Orton, Kofi, Bryan or hell, maybe even a Shield member or Ryback.