Pretty good idea! Blockchain technology is a fairly useful stuff what can be used everywhere where computing is involved. I'm thinking on using it in network/system management tools instead of SMTP, or encapsulating SMTP traps or gets and sets into transactions.
if not decentralized,
open and secured, it is just databases.
call it 'block-database-chain' if you will.
still nothing new.
your right that it wont be open, because it will be the back bone of the banks running only on the banks servers. but with nodes in each branch of the bank means it is decentralised. (just a closed decentralised system (more than one copy of database))
banks want it so that they dont have to worry about their own employee's 'creating money' by just adding values to an account that came from nowhere.
banks want it so that every unit of value has a source and destination
banks want it so they dont have to spend millions on auditors, security teams, fraud squad teams. as the blockchain self regulates every transaction.
so although bank customers cant 'mine' the banks altcoin. and every unit of altcoin is premined by the bank. this means nothing. its not about allowing random people to 'create money'. its about the banks having a fairer back-end that can't be abused by its own staff
