I mean, it kinds seems inevitable to me. Books has become e-books. Cash is becoming digital transfers. China has done it. The west is mostly doing card-swipes. One day, that transition will be complete, and cash would be phased out.
What happens then? Think like the power outage in Spain recently. Some people had cash. But in 20-40 years. There might not even be any cash in existence. What then?
What if, instead of a few hours, its a few days? Or weeks?
I guess riots break out all around the world?
(Seriously, has none of the politicians ever thought about this? Where are the backups? Are we just going full “YOLO” on the reliance on the power grid?)
Same applies to crypto-currencies like Bitcoin - as far as I understand they need constant power and global internet connection to function. Otherwise the network fractures into shards that have different views of payment history.
Maybe if the system breaks, it can be restored to an earlier state, and synchronized with islands which did not have the outage, once power is re-activated.