People like me, where a car purchase is a distress purchase, will probably be the first to change. If you cannot afford a car why buy one. Go down the autonomous cab route. Those in the know reckon it could be on par with a bus fare, for trips around town. Just so much more convenient. This will depress used car prices dramatically, so the people who have bought new will hold on to their cars for longer. When they eventually need to replace their vehicle then they too will go down the autonomous route.
It will all come down to economics. While it is cheaper to own and use your own car then autonomous vehicles wont have a great take up. The first to change are the people who use taxis and Uber style hires. Many of those don't own cars at the moment. The young will lap them up too. Many young people have no interest in learning to drive (I had my provisional for my 17th birthday and was out on the road that morning). My two grandsons have no interest in car ownership or learning to drive. Why should they. They like to go out drinking with mates, they live with their girlfriends (no need for a back seat) and taxis are a way of life for them.
Eventually, and it may take a few years, autonomous car hire will be so convenient and much cheaper than owning a car, so why should want the expense. People may still have the odd car for high days and holidays. Brought out in the summer, just as many born again bikers do with their machines.
There is no denying it. It will happen, like it or not. And probably sooner than many of us think.