I think it's possible theoretically only. People are not ready to stop using banks. Peer-to-peer system is like something mythical to them.
It is possible for Bitcoin to take over a bank but to be honestly think that the change of that happening are almost at zero.
The chance us bigger that Bitcoin would be taken over by a bank.
You are wrong as bank do not work only to save and transact our money , only in some duties bitcoin will replace banks while in all other duties which bans have will remain with banks and for that banks will survive.