The market price of gold has been tumbling. And logic and economics dictate that if the price of gold falls below the cost of mining gold, then miners will stop mining for gold.
If miners stop mining and buyers keep buying, then supplies will be strained and prices should rise. This is the thesis of the remaining gold bulls.
However, the cost of mining gold varies greatly from mine to mine. And as such it is difficult to determine at what price gold needs to fall so that supply-demand dynamics become strained.