By machines, he mostly means simulated brains. I've always thought that a robotic singularity would result in an concentration of income in the hands of the capitalist/owner/shareholder since demand for human labor would diminish.
But I think he is saying that it's likely these robotic-simulated-brain-people would multiply rapidly and would displace us fleshy-brain-people, much like humans displaced their humanoid for-bearers.
But I think he is saying that it's likely these robotic-simulated-brain-people would multiply rapidly and would displace us fleshy-brain-people, much like humans displaced their humanoid for-bearers.