will never happen. bank will stay always. coz its not possible for everyone to use a single currency worldwide. also not all people use a single way to purchase everything. Banks will always win, they have support from the Government and the society.
Yup and banks are more older and stronger then bitcoins and there is no point in thinking that everyone will quit using banks and switch to bitcoins and that will never happen as even in future bitcoin will be having limited users.
And people are more trusting banks against bitcoin so it is not going to happen and people are more used to with banks. And for those people who doesn't even know bitcoin, they are going to think about it that how did it manage to make banks for this decentralized crypto currency that has been established and running within for just few years.
The fact is most of the people are not familiar to bitcoins yet and who are aware about it don't have faith in its ability as they have a feeling that bitcoin will not survive in long term.