IMO unless things get really messed up Gold is never going to be used as Coinage at ground level (public) again.
Now, a paper/digital currency backed by a percentage of Gold/Silver is a much different story (for a time at least). Maybe not so much silver, it's uses in our hi-tec world are far too important for it to just sit around. I think silvers true value as a precious metal is about to be realised.
This is what TPTB are good at...they make the rules. The current money system crashes...they make the rules for the next one.
The rest, as they say, is history!