I disagree with you, people can still change bitcoin even if there were no banks available.
Think of it this way, if there were no banks available, which means there wouldn't be fiat money available too, if this is the case, then there must be a form through which people can buy and sell/exchange goods and services, people can still buy, sell/exchange their bitcoin through that form or medium as long as there's internet available.

Yes, times are changing, and the future is already here, many businesses around the world are now accepting bitcoin and many other cryptocurrencies as a form of payment for their goods and services, and as time goes on, many other businesses will join, until bitcoin and cryptocurrency payments become a dominant form of payment as fiat currently is today.