If human society collapses, our cities and landfills will become ores. Strange ores filled with unnatural mixtures of metals, but ores nonetheless.

The sources you've linked discuss mostly the recovery of additional metals on top of what we have already recovered. That's a different and much harder problem. It's worth remembering that historically, the amount of metal obtained was much smaller — the vast majority of the copper that has ever been mined was mined in the last century, even though humans have been using copper for thousands of years. But historically, that copper was mostly used for consumer products, while today it becomes electrical cables, so it's less obvious how much copper we all use. There's surely enough copper in the walls of my apartment for everyone living here to cook in a copper pan, even though we think of copper pans as being too expensive nowadays.