Possibly he should have said “Forget paper fiat currency”. There still will be “money” in some form. It may be a bag of potatoes or a few rounds of ammo. It will be whatever people find to be of value at the time. But it will be something.
Nameless is on target regarding water…. clean potable water. States are already squabbling over it and people have lost their lives over water rights and protecting their access to water.