We ran out of cheap pure copper a long time ago. Now we're producing copper out of ores that contain a very small proportion of copper. If the price goes up we'll produce copper from ores that contain an even smaller fraction of copper.
Copper is 60 ppm of the crust. As long as the price keeps going up, we'll never run out.
It's also an asymmetric process: getting setup for less pure ore is capital intensive, but once you are the available abundance of your new feedstock can push prices lower then they were before.
Copper is 60 ppm of the crust. As long as the price keeps going up, we'll never run out.