This is the most unpredictable match on the card in my opinion.
While I had strong feelings about who could win the other four matches, I believe that this one is truly a toss-up.
There are several viable scenarios that I could see playing out in this match:
1. John Cena wins starting a feud with Alberto Del Rio, who claims he got screwed out the championship by Edge's retirement (which is actually factually correct if you believe what most insiders say).
This feud could culminate at SummerSlam, and provides a match that most people would want to see with two of the biggest names in the company.
Furthermore, it could be the out needed to reinsert the Rock into feuding with Cena. If the Rock does not appear on WWE TV after this week's Raw for several months, you would have to think he would reappear at SummerSlam in Los Angeles.
He could cost Cena the title, thus freeing Del Rio from the feud with Cena, so that he could focus on other feuds.
2. As John Morrison is about to climb over the cage, R-Truth interferes and stops him from winning the title, allowing either Cena or Miz to win, and furthering the feud between the two.
3. The Miz wins and takes the title to SmackDown because he feels disrespected at the lack of attention he perceives that he is getting (as he said in his promo on Raw).
4. Morrison has a ridiculous spot where he runs up the cage parkour style and escapes as Cena or Miz is about to win, resulting in the IWC exploding at the fact that the Golden Boys (Morrison and Christian) won both titles.
5. Del Rio interferes to cost Cena the title, resulting in a Cena - Del Rio feud and a Miz - Morrison feud.
Realistically, John Cena does not need the title at all. He is established enough that he could practically go the rest of his career without another title reign and it wouldn't hurt him one bit.
Miz and Morrison would benefit so much more by holding the title. It adds legitimacy to the Miz or would help show that Morrison is more than just a "spot monkey."
As much as I don't want to do it, I think Cena will win.
Cena will win because they owe it ultimately to Alberto Del Rio. With his rise as the top heel on SmackDown to his transition to Monday nights, you would think that if "his destiny" is to be fulfilled, he would defeat John Cena to win the WWE title down the line.
Having Del Rio go over Cena would ultimately set up the feud I spoke of above, and would solidify Del Rio as the top heel going forward.
Winner and New WWE Champion: John Cena