This is exactly why it is not worth investing in ripple. Banks are not going to use to use someone else's creation as it is too risky and they have no control over it. if blockchain technology is going to be adopted they will simply create their own coin either as an individual establishment or in a collaborative group.
There's no need to create a separated coin for each bank in order to be in complete control of it. If this happens, bank's won't accept each other's coins, even if they're in the same country and using the same fiat currency.
Banks won't create a coin but will develop a blockchain based solution. People won't be interested in bank coins, they only want quick and affordable transactions. They don't mind how banks would solve this, as long as the service of the banks' is cheap and reliable. Banks can make some advantage for themselves using the blockchain term in their advertisements.