Sounds like an opportunity for an entrepreneur to start an exchange mechanism NOW for the internet, with off-line back ups if internet is gone.
I watched this video about the collapse of the Argentinian economy and they finally have resorted to creating bartering co-ops.
It’s almost an hour long, but worth the time to watch and learn from. You will see this happen in the USA.
Argentina’s Financial Meltdown
https://www.youtube.com/watch?v=QCxbIjYTFQA