The reason why banks will always be against cryptocurrencies is that, since btc in its nature is a decentralized cryptocurrency and that they will not get anything from it when they allow all people to accept it.
I don't think they will be against it because the technology is good and more profitable for them. Consider that in cryptocurrency the transactions doesn't have to be manual and no employee would be attending during the processing which means they can cater to more clients with low human resource to attend to. This is a great advantage for the banks. Second clients can become global so banks can have a wider scope. So I really think they will really use the tachnology for their advantage.