Recently a researcher at Toyota predicted that self-driving cars would perpetuate suburbia and enable more driving. A door-to-door ride in my own car would be far faster than riding the Boston area commuter rail, which has an inconveniently sparse schedule, and then the Red Line into Cambridge. The only reason to take the commuter rail is to avoid the chore of driving. The diesel locomotives are not cleaner or more efficient.
I fully expect that this is correct if you hypothesize the availability of fully (or even largely) autonomous vehicles--however long they take to make it onto the roads. It's only logical. Make driving a "better" experience in the minds of many people in the sense of allowing them to do things in the car other than watch the road and you'll get more driving. To the degree that autonomous vehicles could perhaps ease urban parking, that would make using them more attractive as well.
I don't think anyone really knows how self-driving + electric cars are going to exactly play out in the coming decades, but I fully expect them to make individual car use more attractive, not less.
Nobody knows.
Robotaxis are a bit like carsharing, they change the economics. A private ownership car bears a lot of fixed costs, and each mile get cheaper. Once you own one, you are likely to use it all the time. With pay-as-you-go robotaxis the incentives are different. Going car-free will be easier.
Self driving cars will relieve downtowns/walkable places from dead parking space. That means more destinations reachable by foot/bike. Why use a car when you can use your feet?
Self driving cars also means that roads will be safer for pedestrians and cyclists.
Congestion won't go away. Now you can read/work/play in your car, but that's about it.
Last but not least, sprawl is still unsustainable in terms of infrastructure.
I suspect local economics dominates the issue. Even the ticky tacky hundreds-of-townhouses-all-the-same sprawl into the garlic fields (are there still garlic fields?) south of San Jose will not feel any pinch from... what? San Francisco is full and Silicon Valley spews wealth. San Jose should benefit from higher density and more urban cultural life, but it's not going to make a dent in demand. If the money is there, the sprawl will remain. Conversely, if it isn't, there won't be any urban revitalization.
