Kofi, Kofi, Kofi, Kofi and Kofi.
Kofi's push has stalled big time, and really, I can't see it going any further unless they pull the trigger on him turning heel. This is where MITB becomes important. atm, Kofi's character has turned into someone who will stand up for himself. Nothing groundbreaking, or even really interesting, but it worked for his feud with Orton. However, it's much too one dimensional for anything else to really happen, unless he were to feud with Sheamus who also has that bully type character going on. If not he runs out of logical options. Add in the fact that he's not getting the cheers he was before, and he needs something to be done for him. Thus a heel turn being my idea.
What they need to do for this to be successful is continue to play up this character of him standing up for himself for awhile, while also keeping him close to Cena. Have him and Cena align, with Cena eventually winning the title (perhaps at 'Mania) while Kofi wins MITB. Kofi continues to team with Cena and they play up their friendship, until Cena starts to outshine Kofi big time, making the save for him week after week thanks to Kofi getting beaten down in situations where the heels use a numbers advantage. From there Kofi accepts Cena's help, before eventually turning on him and cashing in MITB, saying he didn't need him and that he can stand up for himself, turning him heel with the over the top "I can fight my own battles and I don't need you" type character. It keeps Kofi's character on track and also gets him over as a main eventer.
Now, as far as me not saying Christian, Miz or DiBiase/Rhodes goes, it's actually quite simple. They don't need it. Money in the Bank should be used as a tool to help guys get to the main event and give them that extra shove. None of those guys mentioned need it because Christian and Miz are already over enough (plus Christian can easily move into the main event in a feud/alliance with Edge), while DiBiase and Rhodes both have a ready made angle with Orton. Giving them mitb would be unnecessary.
Kofi it is.