Banks have historically performed many functions
1) safe store of value
2) transactions through booking
3) loans
1) and 2) are rendered unnecessary with bitcoin. loans are not affected so much, and it is not known how bitcoin might effect lending or financing in general.
there is a much more immediate effect, and that is in connection to the role of central banks and the state. fiat money is linked to the state and its system of control. so people are under control by banks, but more importantly central banks and government. banks and the central banks are essential one system. for instance if most banks are on the verge on bankruptcy the central bank has to jump in to preserve the money monopoly of the state. on the international level the IMF serves this function of a lender of last resort. one could say the world is hold hostage to crazy central bankers and bankers. the situation is much worse than even pessimists realize.
the question you're asking is a good one. I believe it is simply not known what the effects are ultimately going to be. one thing I'm certain is however, that the impact is going to be absolutely enormous. cryptocurrencies have the potential to change almost every aspect of economic and social life. in 1-2 years we are probably going to have a better idea of some of the effects, but the exponential impact is going to continue.
Thanks buddy! That was really helpful.