I literally have no idea, having just had a quick check at the actual active rosters they are so thin on credible opponents for Punk other than Cena I can see them going with something like this:
NoC: Punk defeats Cena by some nefarious fashion
HIAC: Cena defeats Punk to win WWE Title (again)
Survivor Series: Punk defeats Cena by some sort of interference to reclaim the WWE title
TLC: Punk defeats Rey Mysterio & Daniel Bryan to retain WWE Title (a filler feud mainly)
Rumble: Rock defeats Punk (Cena also wins Rumble to go to Mania)
Elimination Chamber: Rock defeats Punk, Bryan, Mysterio, Big Show & Kane to retain WWE Title
Mania: Cena defeats Rock to Reclaim WWE title (again), hell they may even through us a curve ball and make this a triple threat with Punk thrown in (mainly so neither rock or Cena has to take the pin).
When what they should do is keep the title on Punk all the way up to the Rumble and then finally have Rock defeat him, this would give Cena a reasonably credible storyline (similar to Austin back in 2001, needing to recapture 'his' title to reaffirm his place after being defeated by the better man one year ago etc.), or this:
Originally Posted by Tyrion Lannister
Punk holds the title until TLC (is that still the December ppv? Until the December PPV, let's just say), Cena finally wins the title, Cena faces Rock at Royal Rumble, Rock wins the title, Punk gets a title shot, Punk beats Rock at WrestleMania.