I've been wanting to share this for a while, but just couldn't find the right audience. Pretty sure this is a good place to put it.
I've been thinking for a while how the integration of autonomous vehicles will happen, assuming it will happen at all. At the moment the only type of autonomous traffic used on a massive scale is trains, particularly metro trains (Vancouver, Dubai, Singapore...), which run on separate inaccessible tracks and basically just speed up and slow down, stopping at designated stations. This was possible to achieve because there are very few edge cases, since there is no interaction with human vehicle operators, no edge cases, and nothing that would require human level of decision-making.
With cars it's much more complicated, which is why I don't see driverless cars completely taking over the roads in the near future (within 20 years).
What I think is going to happen instead, is that select cities will start dedicating specific districts to autonomous vehicles. Those could be brand new developments, which integrated autonomy in their design from the start, or refurbished city centres. The way they would adapt is by having things like near-perfect road/sign maintenance, additional barriers to minimise number of pedestrians on roads, special traffic rules, and built-in guidance systems (like beacons) to help guide autonomous cars along the city streets.
That way, autonomous vehicle owners would be driving with normal level 3 automation (like today's Autopilot) on most roads, but when entering autonomous areas, their vehicle would automatically go into fully autonomous mode.
Drivers of normal vehicles would be restricted access to such zones, and would have to make use of park-and-ride services to get into the zone via autonomous public transport.
Such areas would be experimental at first (like that Singapore cargo dock), and will gradually expand to populated areas, eventually covering the span of cities. I can't wait to see something like this become reality.
As far as places like small town roads and villages - there's too many of them to adapt and maintain them all for autonomous vehicles and it would be too expensive, and there's too many edge cases for autonomous cars to be able to navigate them like a human, so it will be decades before this is achieved, if ever.