CM Punk's contract with WWE is to end and his world title match against Cena will be his last match in WWE. He vowed to leave the company with posession of the WWE Title, not to mention this match takes place at Chicago, a fitting arena, the the Chicago Made Punk.

do you think he's really leaving?
Are we to get a Chicago Screwjob??
Will he win the title?

If Punk had resigned, we would have heard about it. WWE's philosophy of not mentioning other companies makes it hard to do a Summer of Punk type angle. Punk loses and leaves the company, then eventually comes home to ROH.