They're just so awesome together
Keep them away from each other all year long. Turn Punk face halfway through the year to face Brock at Summerslam.
Give him a redemption storyline about never main eventing WM because of Cena. Face vs Face with shades of Mitb 2011 at 'Mania
Hell no. Taker vs. Cena should headline next year.
Punk/Cena should have been the main event of WrestleMania 27. I thought that was the direction they were going when they had that mini-feud in January and February that year. Especially after Cena's feud with Nexus.