#4 Baron Corbin
Baron Corbin is our fourth choice and can certainly be considered a contender for the championship. Corbin is less likely to walk away as the winner, not because he isn't capable of winning, but for a couple of other reasons.
As it stands right now, he is in the midst of a program with Sami Zayn. Of course, this program will go on for a while longer, but the other reason is that a heel winning while another heel is the champion may not be the direction the creative wants to go.
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While there aren't any certainties that Mahal will retain against Orton, it feels unlikely that they will build up the heel as champion just to have him lose it a month later. Therefore, a heel Money in the Bank contract winner with a heel champion doesn't seem likely.
This would also be a repeat of Seth Rollins as the Money in the Bank contract winner while Brock Lesnar was the champion, which was a rare sight.