On the second part, maybe or maybe not. Punk himself has not done anything to become a non-draw, he just doesn't seem to be able to get to that position is all. And if full show ratings are to be used (similar to how it has been used by trolls against Orton on SD), Punk was unable to help them rise from the get go as the go home show for MITB 11 got right below 3.0 which is not what everyone had hoped for. And he also failed in the ratings department around new year time when Cena took a backseat before his feud with Kane came into full force and Punk main evented with other IWC darlings such as Bryan and Zack Ryder. What they're doing now is trying to get him to become a draw by giving him so much TV time after treating him as irrelevant for the longest time being. It may be too late now and so far, ratings are still down.
Punk last year was incredibly over during the summer and sold great merch for two months, and topped August, this indicates to me, at least, that he could have been a better draw if the "summer of Punk" had gone better. The thing is shortly after that it just ended up with him losing and becoming John Cena lite. The whole return and further storyline was a botch. As for December, while the ratings did suffer, the buyrate was pretty steady, it only fell by a few thousand. But the win came off the coattails of Cena/Rock hype for SVS, so that could be an attributing factor. The main thing though is the fact that Punk was just a shadow of himself as a face and the audience probably didn't care.
As for the future, I don't know either. Being treated as second best and non-main eventing as a champion for nearly a year will hurt anybody. I think you're correct in saying they are trying now to build him as a bigger player than previously, as they now know they need him as the top heel. Feuding with Rock, strong booking(Within heel respects) and a decent WrestleMania program (HHH or Sheamus perhaps?) would be the ideals. Feuding with Rock would obviously be the biggest point of his career, and it would cement him as a top heel if done correctly. It should simply be Punk looking for respect amongst a legend, but he should avoid the "DWAYNE" and "IM ALWAYS HERE AND YOU'RE NOT" crap that Cena and Punk himself pulled last year.