I don't think it will happen with so much hacking and leaking going on with people will still go on the mode of payment that will insure their money, banks are not going to go away but they can add Cryptocurrency to their system and they can co-exist, there are circumstances that bank can only play a role on transactions and there are circumstances that its much better to us Cryptocurrency than bank's credit or debit card, I don't see anything wrong if they can co-exist we are in a modern world a world where people are always looking for a better alternatives.