Even bitcoin having a revolutionary technology, I do not think this would make the banks disappear. Many people still depend on banks, and these banks are institutions with a lot of financial resources, they could find ways to adapt.
It's common to hear news from banks working on projects related to blockchain technologies, for example.
Banks would always find a way to adapt, with or without fiat money being the primary form of their functionality. They would just really, really prefer that Bitcoin doesn't enter the mainstream because if something like that happens, there would be a huge discrepancy with what they would be able to loan out and keep within their vaults, and that proceeds to limit their ability to make money off of FRL.
Blockchain technologies are applicable and useful for them; Bitcoin is not.