Punk wins MITB. McMahon fires Cena. On the Raw following MITB McMahon declares a tournament for the vacated NEW WWE Championship. The tournament will span take place the weeks prior to SummerSlam. SummerSlam comes and you have Del Rio and (any other popular wrestler). Just before the main event you have Stephanie/Business HHH walk out. They declare that they've rehired Cena under a special contract and since he was the last champion he is entitled to a rematch. Cena is added to the match to make it a triple threat.
This would give Cena a full month off and still have the Del Rio match at SummerSlam. This could create a storyline with Cena rebelling against the boss, making him the "underdog" again. I would have Cena lose the match. He would then have a Title Match at the Royal Rumble and win it. That same night Punk makes his return, wins the rumble and declares he's facing Cena at Wrestlemania. Punk can use his belt to declare he's the best, while Cena does the same with his. Now we have a Triple threat match at Wrestlemania. This match would decide who the one, TRUE champion is.