This article in Governing makes the case that a big impact of self-driving cars will be on the amount of land used for parking:

First, self-driving cars need less room to self-park, making it possible to squeeze more cars into a garage — up to 60 percent more, according to Audi. Second, parking garages would no longer have to be located downtown — drivers and their passengers could exit the vehicles in the city and the cars would self-drive to the garages on the downtown’s periphery. Third, with garages capable of storing more cars, cities wouldn’t need to devote so much space for curbside parking, freeing up valuable land for public transit, pedestrians and bicyclists, and reducing the congestion that comes from drivers searching for a place to park…

Self-driving technology can park a car so precisely that lanes with a width of three meters are adequate, leaving just 10 centimeters of space between the mirrors of parked cars, according to Audi. By packing more cars into less space, the company says that the amount of parking can be reduced by as much as 60 to 80 percent in some cases.