I think Cena proved on Raw that he can do a decent promo when he's not joking around or being goofy. Obviously not quite at the level of Punk last week, but still thought he came across quite well.
At first I thought that the 'Cena gets fired' stipulation meant it was obvious that Punk was losing but I read a comment somewhere by someone who pointed out that Vince said Cena would be fired if "Punk walks out of Chicago with the title". I'm thinking they might have Punk win the title, then the winner of the Raw MITB Match comes out and beats him for it.
Or perhaps it's all a big swerve and Punk wins the title and reveals he isn't leaving at all, so Cena gets to keep his job....