It is pretty difficult to say that the Banking system will collapse entirely. The reason for this is banks are pretty active when it comes to money. Right now, They are watching the outflow from the banks which is not being returned to the banks. In the previous days when people used to invest in stocks and forex, it used to come back but now the thing has changed because of the crypto.
And those banks that have realized this have already started to give the custodial services and may adopt the Blockchain sooner. So, They will go with the trend and may remain in side with the all Blockchain based Financial Products.