In fact banks are valued to the profits they make. Transactions itself of money are in fact a cost for them if they dont charge it to the customer. The real value in it for them is making it last a few days until its on their customers account. In those days they can play with the money
But again apart from all of that. They are doing zero transactions today for banks.
I completely agree. Transaction costs are free for bank customers (mostly), while those fees are being paid by the bank. However, banks are "loaning" money to each other at such ridiculously cheap rates (compared to what a consumer might see), and earning ridiculous amounts of money from that because the volume that they're loaning [which I'd prefer to say that they're "floating"] on a daily basis is absurd (which is where some of their value comes from -- and why their deposits are so important; collateral).
Anyway, Ripple is doing zero transactions today for banks. And I don't even know if they have contracts with any banks yet? But they have the infrastructure built, which is the hard part. If you build it, they will come???
To be honest I'm afraid that a blockchain is a very nice invention that is not really needed.
But maybe paradigm will change in the real world creating a super use case for it.
Like always time will tell :) !