They have no use for bitcoin or any other cryptocurrencies. If they had, they would use some closed centralized "currency" like Ripple.
The bitcoin blockchain is a lousy and terribly inefficient data structure. It is used in bitcoin because it was the only structure that Satoshi could think of that prevented double-spend and could be reliably maintained by a distributed swarm of uncoordinated anonymous volunteer miners. The bitcoin system uses the bitcoin currency to motivate those volunteers, through fees and block rewards, because it has no other way of rewarding them. However, the banks will hardly want to use uncoordinated anonymous volunteers to process their billion-dollar transactions. So they will not need bitcoin to reward them. So, after the hype deflates, they will realize that there are better data structures and protocols for their problems -- and that they are already using them.
The tone and substance of your comments come off as skeptical, but far from academic...
You appear to be way too emotionally attach to a goal of denigrating bitcoin that you fail and/or refuse to recognize benefits of peer to peer validations of transactions and accordingly you present your argument(s) in a very non convincing manner.
Even though you may be correct that in the beginning banks will likely hesitate to entrust their transactions to the bitcoin blockchain, with the passage of time, the smarter "banking" players are likely going to come to realize that bitcoin's blockchain can be utilized to their benefit for a much smaller cost and with better security than their own centrally controlled and likely half-baked and likely much more costly "blockchain" imitation alternatives.
Keep an eye on USAA. They will be one of the banks at the forefront.