It doesn't have to be either or, the banking system of the future can be a mix of different technologies. Personally I see bitcoin(and friends) as the higher la

It doesn't have to be either or, the banking system of the future can be a mix of different technologies. Personally I see bitcoin(and friends) as the higher layers of a hierarchy used by humans to securely trade value. The 3rd record of account doesn't have to contain 100% of all transactions taken by it's holders, but when the transaction is big enough, or the values held by 2 parties is questionable because the time since either of them updated the 3rd record has been too long, then write to the blockchain. Most other transactions can be taken care of between the 2 parties without involving the chain at all, as long as in the future someone squashes all their transactions and writes to the public ledger, to prove they haven't cheated or made a mistake.