You will see FED or JPM sell tons of Gold future that might worth half year of production. Or they will tight up the future market with higher margin reqirements.
That will ultimately create a big sell of GLD and SLV. It is like that every time.
To me GLD/SLV has no difference than stock. But they don't pay any dividends. It is the same trade as you buy a stock and expect an upside.