I always thought we would have swarms of nanobots that chewed on the landfills for a decade or so and sorted the mess into tidy piles of pure elements.

What do you then do with the nanobots?

Turn half off and have the other half chew through them, recursively.

For some elements maybe.

Iron, glass, paper and plastic will never run out though. And we already recycle lots of metals.

You would probably like this link: https://en.wikipedia.org/wiki/Plasma_gasification That's how you recycle bulk garbage, but it's expensive in terms of energy, so we have to solve that first.

You need not wait, the future is here today, in Brazil and elsewhere: http://www.wastelandmovie.com/ and http://en.wikipedia.org/wiki/Waste_picker

Yeah, I've been wondering if mineral rights in landfills would make sense as an investment. It's an interesting collection of stuff-humans-once-had-use-for, and as recycling tech improves...