The preliminary Caixin/Markit China Manufacturing Purchasing Managers' Index (PMI) fell to 47.0 in September, the worst since March 2009, missing market expectations for 47.5 and slipping from August's final 47.3.
I don't know where you heard that but that is completely false. The only futures contracts that settle for cash are things like volatility. You can't deliver volatility to someone.
There is no shortage of metals, or any other commodity, at the wholesale level.
If you want to take delivery of a commodity and someone else doesn't have something to deliver, the price goes up.
There are not two gold (or any other commodity) markets physical, and paper. No one who is trading professionally, or on Wall Street, believes that.
There's a Delivery Notices section on this page about how much metal demand there is: