It cant because old people and big fortunes are stored at banks, soo it wont happen at all, as some people said in the past save your money at the banks and enjoy the fees they pay to you, since they lend your money to others. Even the p2p transactions does requires bank, without them bitcoin would be dead since we need to transfer money between accounts. Bitcoin wont replace anything, it can improve all services as remitances, providing a fair system and not abusive charge due to cambio.