It took centuries of trial and error for most countries to come around to their modern systems of money. Central banks today monopolise national currencies, and they steer availability mainly through commercial banks that, as economists often put it, 'create money out of thin air'. That is, centrals expand or contract supply by lending to and imposing reserve requirements on commercial banks. I think cryptocurrencies are going to end up as an alternative option like several categories. It will end up existing alongside traditional forms of old banking.
On point! Fiat money will always have use, especially for the poor, because it is the easiest to acquire and and it is not complicated to understand and use. Unlike for virtual currencies which needs internet connection, a decent device and technical knowledge of the user. It will just like be paypal in a sense. But I don't deny that bitcoin is gaining ground in terms of value and usability. It may or may not be the main currency, but fiat remains as long as there is a demand and of course, banks.
Banks will try to adopt to the changes of the financial climate to survive. Those who are not willing to adopt are those that dies. ex, Nokia and Blackberry. In fact, they already tried to adopt. Example, Ripple.
Good outputs. In this world we are always adopting this banks soon enough they will use cryptocurrencies they have nothing to do with the people who use crypto and for those who's still not using crypto may use fiat as an exchange. In fact it was not too easy to make it change fast. Even the government in every country will take time to adjust the currency system. Many will go and change not only in the transactional methods.
Let it happen banks will be banks they will going to change upon situation on what most people were liking that which can take advantage.