The author makes the implicit and false assumption that humans will always be able to compete with machines in something that other people are willing to pay for. That has been, and probably still is, the case. I see no reason to think that will continue indefinitely. Humans have three key properties that have kept us competitive with machines:

- "Intelligent" observation-based decision making

- Flexible manipulation of objects

- Teachability

Technology still have some way to go to match our capability here, but they're getting there. The dynamics are roughly that humans improve or change linearly through education, but technology can improve roughly exponentially.