Do you believe, in a complete collapse, that gold won’t be the new currency? Of course it will.
Pre ‘64, U.S. silver will be king at the food market, and gold will buy you a house, farm, mansion, aircraft, whatever.
I doubt there will be a time when gold is not accepted as legal tender, worldwide.
Your notion that there will be a worldwide trade in anything except seashells after fiat currency collapse is amusing.