Blockchain technologies could reduce banks' infrastructural costs by $15-20bn a year by 2022, a new report from Santander InnoVentures claims.
http://www.coindesk.com/santander-blockchain-tech-can-save-banks-20-billion-a-year/Do you realise how much money is that? With such savings,the bank could raise bank deposits interest rate or lower the loans interest. That refers only to some banks,there are some who just want to keep the profits for themselves. 
Everyone will be using the Bitcoin blockchain to run their banking infrastructures, because it doesn't make sense to use any other blockchain. Not using the Bitcoin blockchain = guaranteeing your shit will get hacked. For some reason they STILL keep the "blockchain tech" thing but tend to avoid the part where a cryptocurrency is basically the fuel that keeps the blockchain running.