we won't be too far from a time when we'll be paying for things with foreign currency.
i could see going to your local gas station for a fillup, and the guy won't accept your credit card (if you're lucky to have one by that point) and won't take paper dollars. but he'll be happy to take swiss francs or hard barter ... like plugs.
if you think this is b.s. ... consider that in Europe, some retail establishments are no longer accepting credit cards for payment! No $hit!