Indeed, but isn't the economic value of a competent programmer tied up in speed and motor efficiency as well as the domain knowledge? How does that equation change with disability, I wonder?

My personal sense was that if my hands or my eyes ever became useless (e.g. RSI, worsening eyestrain issues), I'm finished.

Correct - its a slower process but it can be done. Programming is all in your head, how you get it into the computer is irrelevant (recall programmers used to use hole punches on paper). I suspect that we'll have non-invasive mind to computer interfacing before my hands give out anyway.