Some relevant considerations:
- Gold is really valuable. The current spot price of gold is around $1200/oz (as of January 2017). This may make small transactions difficult - you'd need the dollar to collapse to the point where people just stopped using it, AND something like a food shortage.
- I can't find a source for this but I'd bet most Americans don't own material amounts of gold.
- Silver is a much more convenient metal for small transactions, since its spot price is more like $20/oz
- Substantial competition from Bitcoin, at least if the internet's still on.
- Barter, gift economies, and other pre/nonmonetary means of cooperation are also competition.
- There are a lot of places in the US with >1000 people. So, there could be a town full of goldbugs already doing this.
- Gold could be good for large transactions (like buying passage out of / into the US under very bad circumstances), in ways that don't get picked up by the exact condition being voted on.