I've heard many CM Punk interviews, and he seems way to faithful to WWE to leave, and he has a list of things he wants to accomplish, as he happily stated that a few months ago. And not only that, he stated many times that he did ALL there was to do in ROH and Japan, so he's not going back.
And even if he doesn't resign, it will only be a break, much like Chris Jericho did last year. CM Punk is not going to ROH or TNA, I know that for sure.
Actually, you don't know for sure. It's like Sting said once, "The only thing that's for sure is that nothing's for sure..."
It's not a given that CM Punk is going to stay with WWE, it's very likely, it's the best possible outcome out of all this, but it is NOT a guarantee. Nothing is ever a guarantee, I don't know CM Punk on a personal level nor do I claim to, however if he were to leave WWE, I wouldn't be surprised.
Whether it's a return to ROH or TNA, I couldn't tell you for sure, the rumors about his ring name controversy with Vince have been one of the biggest reasons for a potential departure, and you know what if CM Punk does leave for that reason then good for him.
This is why, he might have a great six figure income coming his way if he were to stay with Vince McMahon but if he were to give up his ring name well that's going for short term gain that can result in a big picture loss.
Think about it like this, despite what most people want to think WWE is NOT the ONLY place to wrestle, sure it's the most recognizable place to be, it is THE organization.
However, if CM Punk were to lose the rights to that name it would cost him dearly in the way of promoting himself for non-WWE sanctioned events and that's one thing I don't think a lot of the people bother to keep in mind. Granted WWE's money might be the best out there, but it would cost CM Punk dearly if he had to give up his ring name just to get a nice paycheck with WWE.
Especially when you consider it was CM Punk that created the name in the first place, it's his choice to do what he wants, but he stands to lose more in the long run than he could ever gain the short term with WWE. If he can find a compromise with WWE than it's all well and good. However, if he wants to do like what MVP did and go elsewhere that's just as well too, he's an entertaining as hell performer and I don't think he's going to go the poorhouse if he leaves WWE.
You really can't speak on any true authority on what CM Punk is going to do unless you are the man in question.