Dude, it's not that we're gonna be in Mad Max world where bullets and food are more desirable than abstract metal.
Nor is it the case that the entire world will be impoverished.
IMO, it's very specifically the US Dollar that will collapse. BRIC economies and the EU will take a minor hit, and after a few months, they'll be fine. The USA, meanwhile, will face massive joblessness, massive inflation (probably not hyper-inflation, but that's possible), etc.
Greater Depression, yes.
Mad Max, no.
You know who got an assload of wealth in the great depression? People who had enough money purchasing power socked away to buy property for back taxes and 1% of the pre-depression price.