Central banks are now the dominant structure that nations use to manage their economies. They have monopoly power and will not give up that power. While the adoption rates for Bitcoin and other digital currencies are small and the government's support for them is virtually nonexistent. So it is impossible for BTC to kill banks, which in my opinion is most likely one day that central banks will issue cryptocurrencies.
It will not be killed but atleast we have already an option now to stay away from banks that feels that we are so entitled to please and wait for our turn to give their service to us. We're so done now in long ques and many times of lag and maintenance of their mobile banking. I'm trying not to use banks every now and then in sending payments or paying bills but there is still need for ATM Machines for some cash. Soon if bitcoin ATM will be present in many area I can say that many will be curious and might switch into it than banking.