In an hypothetical future where society has completely broken down because of extreme concentration of wealth (and means of production and everything) I can see there not being any possibility for a human-based society. In such a doomsday scenario, regular people wouldn't be able to trade anything because they wouldn't be able to produce anything, because all the land will be taken over by the very few ultrarich. Nowhere to live, nowhere to grow food, etc. Essentially surplus population. No government to protect you either, since it will have been coopted by the ultrarich (essentially, them becoming the government). Enforcement could be done by robots, and robots do not revolt or go on strike, nor will they question orders. Maintenance can be done by other robots, harvesting, even health care for the ultrarich.

So how (in this admittedly doomsday scenario that I hope won't come to pass) will a human-based society be able function?