Our best case scenario would be for precious metals prices to plummet: that would indicate that the markets were doing well, inflation was low, and you could back the truck up waiting for the next time the world flirted with disaster. I don't see that happening, but it's nice to think about.
But that would also necessarily require that something were to actually begin to be introduced to support/back our fiat currency and thats even on the horizon let alone in a position of becoming a reality
The saddest part of this is that it would be so easy to make the USD the currency that the world has the utmost confidence in......by simply announcing a program to add PM to back up some infinitesimal small % of dollars in circulation it restore confidence, drop inflation etc etc.