In practice extreme inequality of commodities remove those commodities from the general purpose commodity market. Do you buy food with baseball cards? Do you pay the rent with beanie babies? Is your 401K in collectible Elvis plates?
Or lets look at it from top down, instead. Currently the marketplace for fine art is irrelevant to the general population. Lets say a Picasso sells for $100M in a trade between two billionaires. Frankly no one on the planet cares. Picasso's are no longer an economically relevant commodity currency. Who in America owns more than $100M of confederate money? Some coin collectors might know, but its not worth as much as you'd think.
This is where the dollar, or perhaps currency as a concept, is inevitably heading. Eventually someone in America will collect all of what we call money in 2017, one guy will have all the money, and frankly it won't matter because we'll be living day to day trading HN Karma or whuffie or bitcoins or ... The point I'm making is hyperconcentration of wealth doesn't mean the death of the economy it means the death of that form of wealth.
Is collectible Dale Earnhardt memorabilia still wealth? And if it died as wealth does it matter to you today (assuming you weren't speculating in that market?)