Big/medium banks are never going to use Ripple, theyre only trying it out and will drop it then make their own technology (not de-centralized!)
Blockchain will change how we send money, but not through banks. Theyre completely against de-centralized control of financial system. We need blockchain solutions like Kora (
https://bitcointalk.org/index.php?topic=2876521.0) that are person to person and small business to small business
Private blockchains doesn´t make any sense because why you need a blockchain if it is not a decentralized? Database is much better for these purposes.