Precious metals always retain their purchasing power, even in a Mad Max scenario like the Serbian civil war where a city was surrounded and people were left to starve. I read a report from a survivor. Cash turned nearly worthless overnight but as long as you had a gun, you could trade your gold for food, ammo, batteries, medicines, hygiene products, a helicopter ride out, etc.

I do agree that this time it won't get that bad though and if it did, people would band together against the common enemy.