i do not think so that bank can disappear by bitcoin , hope that they will work in cooperation with each other, and bank will accept bitocin for deposit and withdraw.
It should not disappear because we need banks for bitcoin to exchange and banks are still more safe area to save our money unlike bitcoin that you are saving your money in online that you dont know it will stay long or not.. so bitcoin will be still stay and we need this banks for loans and savings..
But I think if bitcoin gets widely used and accepted in future then we don't need banks anymore as we can buy anything directly using bitcoin without converting to fiat, and it will reduce the customers of banks for sure.