Z060, I wish I had your worry, I do not own bullion, not a smidget, just PM shares.
As for fiat currencies, the dollar will exist, perhaps as an Amerro, but it or it's equivalent will be around. Paper 'money' or it's equivalent electronic credits have to exist but what it means is that silver and gold will be priced much higher.
Silver due to it's larger volume may become a day to day currency in the form of coinage while gold as reserve backup for the fiat at central bank level (somewhat like now).