I think what we'll end up seeing are the developments of sensors and protocols that are invisible to people, but can be sensed by cars nearby. Traffic lights and road signs will have sensors that emit electronic messages identifying what they are and what rules they are communicating that self-driving vehicles should obey. Other cars will start to have them as well. We may even see small barriers constructed between roads and sidewalks that exist only to discourage pedestrians from entering the road to make automated driving even safer. Your vehicle will be rented from a third party. The owner will legally have to have it registered with the city so that the interior cameras can conduct facial recognition to identify the drivers and passengers. Law enforcement can remotely disable a car and could also send signals to get all other cars to pull over to ease the arrests of carjackers and other criminals. Possibly coming to a small town near you.