You might want to consider using electricity for lighting and a bunch of other things rather than block chain during the end of the world. I bet Mad Max would make an interesting movie with a bunch of guys in cars with low end laptops trading water and gasoline for cryptos.
An argument could naturally be made for cryptos that are less demanding than bitcoin in a less dystopic but not ideal future.
Hi! and yes, absolutely! First the basic stuff (often in accordance with Maslow's hierarchy of needs), but at some point, trade is inevitable for human evolution and existence. And with trade, -if there is a rudimentary internet with some power available - why not fire up a cheap and super-effective DMD-node for all your trading needs! That way, you circumvent banks in many ways and keep a middle man away/out. Dont forget that cryptocurrency is a new asset class, the newest that exists and will be with us in one form or other for all of eternity as long as the cryptography of the tech works (which it will) and the need for trade exists (which it will) Best regards and thanks for you comment