Won't non-driverless cars go extinct anyway, since cars don't last forever? Also I think horses are banned on some streets these days, like motorways...
It also seems to me that the transition to driverless cars will probably sneak up on us: "normal" cars will become more and more intelligent until suddenly they can drive without human input.
I don't think they will ever go extinct, although they might gain significant market share. The AI that driverless cars is using is experiential, not symbolic or pure logic...after accumulating enough experience with a certain situation, it knows what to do. This means that any situation which with there is not enough ability to train the AI would be poorly handled by the AI.
Think of a electrical utility truck. They need to do way more than just follow the rules of the road...and in some cases they need to break the rules of the road.
It also seems to me that the transition to driverless cars will probably sneak up on us: "normal" cars will become more and more intelligent until suddenly they can drive without human input.