Darn, my answer was too long and HP wanted me to create a hub, so I did. Anyway, this is the first and last part.
I had done some reading on this but went back for some quick refresher. I don't think anybody is advocating going back in time when trade was done in the actual metal; that, I believe, would be a physical impossibility. So, what the proposal is, is to go back to the Austrian school of thought which is the gold standard.
[In a nutshell, I said - Tagging the dollar to gold didn't work and it won't again. Also, the price of gold fluctuates with good times and bad times.]
So, what will happen to the price of gold when the world economy stabilizes and things improve again? It will plummet as it has always done once people feel somewhat safe again. So, long story not so short, I don't suspect fiat currency to ever disappear.