How does gold trend to zero? We've already minded like 70-80% of the earth's gold, with pretty high confidence.

Of course asteroid mining could change things, or maybe some large deposit could be found somewhere totally unexpected vis a vis the modelling—though even that wouldn't likely change things by more than a few percent.

So the scarcity part seems pretty legit. And I don't see our race falling out of love with traditional concepts of jewellery anytime soon, to say nothing of gold as an accepted abstract store of value.