Platinum is likely what they would mine first... (oops.. that'll come with a fair bit of Pd). Of course, it will drive down prices - the question is how much. Lots of analysis has been done.... although I fear any rigour and the odd mathematical equation will scare off the "independent" thinkers here! Science... pffftt
If gold goes north of $2000, you'd just see a LOT more mining here on good old planet earth... there's lots of gold out there... and prices would revert down again.
technological advancement is the economics logic and rebuffs the gold-bugz dreams(z?).