Punk's announcement is going to be about how he deserves a title shot, what else would it be about. His character has always been about how he is so much better than everyone else and seeing how he beat Cena last week what other logical thing could it be.
He isn't going to go to IMPACT Wrestling, the very idea is so incredibly stupid I can't believe you people are even entertaining it. If he was going to leave and go somewhere else it would more likely be ROH or something like that, but forget all that because the whole thing is a fucking work! How can you not see that. Face it, he wouldn't be on TV getting a win over Cena and teasing a feud with SCSA if he was really thinking about leaving now would he, no, it would be quite the opposite. He'd be in some lame program loosing matches to Evan Bourne or some other jobber, getting buried so his leaving the company would be less impactful, like MVP.
Furthermore, if Punk is going to feud with Austin, and I think he will, it's going to be a Wrestlemainia, not on Raw. Couple that with the Cena vs Rock and you would get 2mil + buys.