In every business it's the same. When new technology comes up the existing businesses will evolve or die. And obviously new businesses will also rise strong.
Same happened with mp3 and music industry...
You are right about the advent of technology and its impact on the existing market but one should not forget that banks are the financial institutions set up by the government and follow the rules and regulations the federal bank sets for them which runs the government. SO in my opinion, banks will never perish just because of the arrival of crypto. It has been a decade since Bitcoin is rolling in the market but there are still lots of banks in Time Square NY and in my country.
Yeah they'll adapt. They are so deeply ingrained in society that they have no choice but to adapt. People depend on them, especially those who cannot handle their financial choices by themselves. It's like the hospital. Some people will go most of their lives without ever having to visit it because they will live very safe and healthy lives and take care of themselves independenptly. Some people will never go to the bank because all the money that they need is in their pocket, and when they need more, they go to work and put more in their pocket.
So banks will provide a similar service for those who want support with their crypto investments and day to day transaction needs. They'll be there to provide advice (which probably won't be very helpful) and to charge service fees for anyone who wants it.