John Law's scheme failed due to a combination of hyperinflation and suspension of specie payments, not because people apriori trust precious metals more than fiat. Typically, liquidity is the main factor determining the choice of a medium of exchange, not whether it is fiat. This is recognised by all the economic schools that I know.
I don't think that liquidity is a problem with gold/silver. It's same as bitcoin, you can always use a fraction of gold/silver to present its previous value
People usually want to regard official money as an unit of count and that unit itself should be constant in value from convenience point of view. In that case the only way to increase money supply under a gold standard is to dig out more gold, like California gold rush
But to utilize people's impression about fiat money's constant value and create lots of fiat money for the banking class without causing inflation, that is another thing. If everyone can own the FED through buying their shares, then any extra profit they made from printing money will go into everyone's pocket, that will be a much better system
