In that kind of world… what happens to gold?
Well, I can assume that gold will not depreciate to zero, because this metal has many real applications for humanity, which means there will be demand for this asset. Perhaps gold will cease to be used as a reserve asset in the future, but as a resource asset, like oil or timber, it will certainly be. And therefore, it will cost N-th amount of money.
It seems to me that they will not abandon gold so quickly because "gold" is in the hands of the powers that be and these guys will not allow gold to be replaced by a bitcoin so easily.
As much as I'd like to see bitcoin thriving, I can't see people abandoning gold. Aside from the real use case that it has although not much, gold has been a reserve for a long time and so far gold is pretty stable and still function for hedge against inflation perfectly.
I believe that bitcoin will be there alongside gold for global reserve, both got the characteristic of scarcity and also got big demand.
We can always have both as global reserve, it decreases the single point of failure as well since we got diversification for the global reserve.
Just because bitcoin become global reserve doesn't mean we will just let gold go.