Think he means low hanging fruit?

> Which "free spaces" are running out where?

Not OP but the college entrance scandal is a great example. With the super wealthy taking up all the philanthropic entrance positions the "just" wealthy set had to resort to cheating and rorts to ease little Johnny Blueblood's way into society.

There is only so much room at the top.

Huge impact technologies like the steam engine, the factory line, electricity, and so on, that are not just incremental steps, things nobody asked for with minimal utility ("smart fridge") or glorified stupidification engines (the social web).

Steam engines existed in ancient greece. It took a couple of incremental steps until they were good enough to kickstart the industrial revolution.