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.