At this rate the only thing that can/will save him is a program with Rock and/or a proper Mania main event program with Brock/HHH/Taker. I don't know what else they can do to get the message across tbh. They've paired him with Cena, Bret Hart, now Mick Foley. What more can they do? What other legends are left you know? Austin? It's got to be the residual effect of completely ignoring him for 9 months of his 10 month title reign. They can't just undo what they've done during that time. As THE main storyline and focus of the show this past month, something isn't clicking.
Honestly, the thing I have always come back to is the complete botch they made of bringing Punk back, FAR too early. The "leaving" with the WWE title should have spanned much longer. Many people, including myself thought he would be gone for 2-3 months or such. Punk even said he was promised time off. They could have built a longer storyline, with run ins from Punk causing big issues, such as costing Vince's "champion"(Cena, Vince says he is the only one that can solve the mess he made or a big-time heel, who Vince trusts over Cena)matches(in favour of incredibly over babyface). Simple stuff like that, until later on Vince gets fired and then Punk returns at the end of a PPV where we see Cena win. However, WWE always like to pull the trigger early when they are sure of something. And again, this was the case. They decided to capitalize on the rematch and his overness as fast as they could.
As for the whole "LOL HHH BERRIED PUNK AT NOC" argument. As I have said before, that was another big mistake in the storyline. Not necessarily having Punk lose at NOC, but the entire balls they made of the afterwards. Punk apologises, and turns into John Cena lite. We saw during July-August how effective and over Punk was as the "edgy" babyface. Simply being Punk. As for the quick post-NOC babyface turn the casual audience were not getting fully behind this "edgy" Punk. Being a sarcastic and witty dick to the babyfaces did not mull over well with the casual audience, despite how much better of a character it was for him. I think the best measure here was to turn HHH heel and have him take the title from Del Rio and have the storyline be "HHH was the liar all along".
I think the entire reign he has had, and his entire treatment(of being 2nd place to Cena) since post-WrestleMania moreso, has left the audience with the idea of "meh". They dont lose anything if they dont care for him, as the pinnacle and most important part of the show was Cena. However by that time, Punk was not making as much money at all compared to Cena, his summer "spark" had been whittled out. They sadly had no choice but to place Cena above Punk leading out of Mania.
Is it too late for Punk? Who knows. He could find and rebuff his entire flare again. But what will it take? The only possible answers, that are possible in the near-future, I can see now are:
-Beating John Cena cleanly
-Feuding with The Rock
-Teaming with Brock Lesnar
We will just have to see how WWE executes this going further. But it is looking rather dim.