On survivalist forums, people seem to expect that in the sort of situation you describe, armed gangs will take over. I don't know whether that's true, and as some of you know, I'm like Dagny in that I don't do long term preparation (too much for my budget). What if Humungus shows up with his gang of marauders? Are you prepared to repel an armed invasion by an organized, possibly mechanized group that outnumbers you?