The probability that humans are still driving around in cars, self driving or not, in 1000 years is incredibly unlikely.
His question is - can your mind wrap around the amount of progress that can happen in 1000 years? If yes, can you imagine that going from "now" to "fully automated cars" is a small amount of progress, relative to progress that's possible on 1000 years? If yes, great - now you can dial back that it probably won't take 1000 years.