That is not going to happen in our life times!! There are to many older people who do not trust much, let alone something they can not see such as Bitcoin. There are also to many money hungry people out there who are not willing to let the money from bank fees go away.
I also do not think this is very gonna happen because its simply not easy to do and the bitcoin has than to fight up against a higher power and that is simply not reachable.
Bitcoin is too small in compare to the banking system as a whole and replacing banks is something out of the reach of bitcoins and banks will always be ruling the world even if bitcoin gets more popular in future.