Dont u get VISA position? If is separable who runs the servers secure the chain? VISA of course. And they'll charge 2 to 5 pct per txn for the service. TBH a blockchain backend would be a lot better than a sql db to store financial txns... so it is not all bad.
Financial transaction DBs aren't typically SQL and are more often journaling DBs like the block chain already, but without PoW as they trust their systems.
You can have journaling with SQL I think. But the point is not so much the POW but the key signing required to change an account balance. With journaling you can use the journal to trace the fraud provided you notice it. With blockchain you stop it from happening in the first place.