And you think the average non-technical person is going to trust that over... trading for actual goods like food/fuel/livestock? On what planet does the government-backed virtual currency fail and then non-technical people suddenly trust a darknet currency backed by... imaginary computer algorithms that they don't understand and don't want to understand?
Some day every phone may have a bitcoin “wallet” that connects to nearby towers using the phones antennas. Everything will “just work” as far as regular users are concerned. You would be able to pay for good just by scanning a QR code on the other party’s phone, for example.
I would imagine that that the point is less the practicalities of how it would than exist rather that commodities will become (as they always have done) the mechanism of trade. Before there was money there was just normal trade. In apocalypse land who are you going to let into your group of survivors, the guy with 10,000 bitcoin on a usb stick or the guy with 10ton of rice?