It often seems like common sense to believe that if a society gets really good at doing something, then tons of people are going to be doing that thing. But oftentimes the reverse is true. Vastly improved agricultural productivity means fewer farmers. Improved industrial productivity means fewer people in factories. And, indeed, improved information technology will in the long run mean fewer people doing information work. Consider that there used to be a very robust “information economy” of people answering phones and taking messages for executives, taking dictation, managing vast cabinets full of files, correspondence, etc. But now computers and voice mail and so forth take care of a lot of that work.
The future is likely to entail increasingly numbers of Americans working in fields where we’re not seeing any dramatic improvements in methods or technology. Teaching preschool. Cleaning houses. Cooking food all up and down the scale from lowly burger-flippers to high-end chefs. Taking care of the elderly. That sort of thing.
On the other hand, agricultural productivity could suddenly plummet when we run out of cheap oil, and we might need more farmers in a hurry.