If you look at the big European cities, real estate is expensive wherever there is an acceptable train or subway connection to the city and prices fall sharply

If you look at the big European cities, real estate is expensive wherever there is an acceptable train or subway connection to the city and prices fall sharply outside of these zones. Self-driving cars will equalize this and it's a good thing. If you can take an affordable self driving taxi to the city you don't care about train connections any more and the key factors for choosing a home outside the city will change.