I'm calling it right now: Since the John Laurinaitis and Cena match has rules stating that any wrestler who attempts to interfere will be fired, here's what will happen.... Big Show will come to the ring, seeing as how he can't be fired because he already "is" and something will happen and Cena will lose the match. Laurinaitis will re-hire Big Show and I can see him being Johny's personal inforcer or something along those lines. Who knows, Show may even purposely cost Cena the match.
His character has been the same for awhile now so I'm guessing they are doing some sort of storyline to turn him into a "beastly" type of big guy rather than the happy go lucky giant.
That's my prediction.