Financial institutions are not going to disappear, crypto or not. The are an essential, integral part of the current economic system. Retail banking is just a small part of it, financial institutions providing capitals for corporations are much more important, and crypto is of no danger for them.
The banking system is very much important with the Bitcoin crytpo currency trading market, not to mention the important of Financial Banking System of its country, this the soul of one country economy. No country can survive with out the Financial institution or the Banking system, they are the one in charged on money circulation, control of possible over supply or over circulation resulting to inflation which bad to its economy. We have to accept the facts that banking system will remains as the growing acceptance on crypto currency trading transaction is very much visible on the market treed.
Without banking system, you can't deposit money to your exchange and you can't take your money out to your account. Banks are needed but their era will end within years with the rise of blockchain technologies.