How Autonomous Vehicles Could Transform the Demographics of US Cities

Cities have historically been shaped by the way people travel. American cities have morphed and expanded with changes in transportation systems from the walking city (pre-1880), to a period with streetcars (1880 to 1920) to our current automobile city (post-1920 but mostly after the freeway era started in 1945). The dense mixed-use agglomeration of residences and workplaces in the pre-automobile era have now been broken up with the addition of sprawling suburbs and dispersed industrial districts. If shared driverless vehicles turn out to be as inexpensive, convenient and safe as expected, and they become the dominant mode of transport for a large section of the population, how would our cities change?