Ohhh I love weirdo hypotheticals like this. Ok so we have like 150k registered members right? Man, that is nothing. And what percentage of them actually have any idea about how true infrastructure works? I mean, for the most part, we'd all be inheriting a world that would rapidly deteriorate around us as things fell into disrepair/out of maintenance. A giant percentage of people would likely starve and die pretty quickly.. turn feral, etc. There'd no doubt be a lot of hostility, I expect there'd be territorial spats/hoarding of resources and a giant amount of the people who are left would die in months, if not weeks. I don't think people would go completely extinct, but basically those who would survive would probably be the strongest/bravest/those who could do well in the wild. Probably farmers and such, people who are used to living kind of out in the sticks already. Would love to see a movie about something like this, although it would certainly be depressing (yes, I know about The Stand, which I enjoyed, but that is still too supernatural).