In fact, gold is already somewhat losing its purchasing power with time. If we look at inflation-adjusted gold prices, gold has been underperforming against dollar inflation since early 1980s. Yes, its has risen a lot in nominal terms but it looks like people are losing interest in precious metals at large. It may be just a slow-oozing and long-lasting effect of gold being stripped of any monetary value after it seized to be a dollar backup.
I'm not sure what you mean by underperforming against dollar inflation. Since the postwar Bretton Woods period, an ounce of gold has gone from $35 to $1300, whereas $35 is still $35. If you mean something else, the early 80s were a bad place as a starting point, since gold dropped more than 50% immediately at the start of that period.
We can then take 1971 as a starting point.
I mean inflation adjusted prices, of course. So $35 back in 1934, the last year when gold had actually been backing up the dollar en masse, is not the same $35 as today. If we strip dollar of its inflation, we will see that gold didn't rise much in real prices. And if we take time period from 1981 till nowadays, the US government bonds, for example, have been performing better that gold. The treasuries are considered a hedge against against dollar inflation, that's what I mean by gold underperforming against it. That is, the treasuries were a better hedge than gold.
