I think the reason that no one on the current WWE roster can reach that level is due to no one really getting pushed to the moon, on Raw.
Sure, Punk has been pushed pretty hard, but has he been pushed like Stone Cold Steve Austin, was?
When it comes right down to brass tax, Cena's run isn't over, and that prohibits guys like Punk who the only next logical step for him would be to become the #1 babyface and run Monday nights.
They can't commit to someone like Cena, because Cena is still there, and they can't properly move into a different era because he is still there.
Rest assured, when it's time to move on to another big babyface, it's going to be Punk. It's like the awkward period right before Bret Hart turned heel, right before the Attitude Era. After SCSA won the King of the Ring and pinned Austin 3:16, it took a couple of years for the new era to really reach it's full effect.
Punk is going to need a Rock level heel before the E can move on to letting him be SCSA, in his own right and so to speak. Cena right now is playing the Bret Hart role, and I don't see anyone as the Shawn Michaels character. None of this is exact, but I do find parody in the situation.
So, in my eyes, Punk is going to be the next main crowd favorite, once they're ready to move past Cena, but I can't tell you who his big heel will be. I don't think it's Miz, right now. He's good, but he's not the Rock and I don't think he ever will be. He had his chance to become that level of a star at WrestleMania, and I think it's clear that he got lost in the mix. Blame the WWE for that, if you want, because I do think they always own some of the blame, in that. But, if he were as good as the Rock, he would have stood out.
Especially as a heel, the Rock's greatest strength has always been his ability to stand out. Like I said, Miz is pretty good, but he can't do that. I know of course I'm talking about a once in a lifetime performer like the Rock, but Miz couldn't stand beside Cena at WrestleMania, either.
Honestly, for what my opinion is worth, and I won't say when it will happen, Punk will the new SCSA and Cena will be his Rock, once he finally becomes heel. You know that as soon as Cena finally does, and I believe he will, though I don't think it will be soon, but as soon as he does, Punk will be his first big rival. I seriously bet that the main event of WrestleMania 29 is Punk v Cena, with Cena as the heel.
It's a stretch and I know that, but that's when Punk will be the #1 babyface, when he beats Cena for it. SCSA had to beat Michaels at 14 for it, Punk will do the same. Then, who knows? Punk's true heel of the future probabaly isn't even on the roster. Rock wasn't on the roster when Austin won King of the Ring, and I think the same could ring true. Punk will beat Jericho, he could possibly beat a Brock Lesnar, at some point, but he'll have a beat Cena.
That's my take, at the moment.