The CIA is running their operations on the cloud. If the CIA can do it, I'm sure a bank can do it.
Are we talking about the very credible agency that claimed that Saddam had weapons of mass destruction?
I'm skeptical on the wisdom of outsourcing the heart, lungs and spine of a company. Once you commit to a particular provider, you might become their slave, forever. On the other hand I'm also very (very!) skeptical on their ability to successfully overhaul their systems internally. After decades of "it's ok do nothing" they would have all of a sudden a revelation? That would mean getting to know who does what, who can do what, who should do what, and have skills development on a continuing basis. Yikes... I'll get my coat!
Biting the hand that feeds IT
