yes that is right that bitcoin can replace banks but the banks cannot be disappeared by the bitcoin network because the banks are the most reliable place to deposit your money not bitcoin. in that bitcoin network your money is not secure because of bugs and fake members and especially the hackers. your account can hacked or money could be lost if password is lost or acount could be deleted. but if banks lose your money it is responsible to give you your money.
in bitcoin you can not retrieve your money.