Autonomous cars will clog up existing cities by cruisnig around looking to pick up rides or deliver shit and mill around endlessly or occupy every piece of parking in prime real estate to make sure they are quickly available wherever demand is high (i.e. where people want to or have to be). In time they will phase out human driven cars which will lead to higher speed limits and more infrastrcuture that supports autonomous driving. Meaning fewer "difficult" intersections, straighter roads, no bike lanes or pedestrian sidewalks. Everything optimized for autonomous cars to endlessly mill around. People will be blocked from being near autonomous cars as those will be going too fast for human reflexes to cope with so areas where cars drive will not have sidewalkss nor bike lanes. This will lead to urban areas that are even more car dependent with only pockets of urbanism that support human scale. To get anywhere one will need to hail one of those autonomous taxis and then zoom in it to a destination where it's again safe to walk in whatever pocket of human activity. Since cars need a lot more land area than humans the urban infrastructure will mostly cater to them and not to people because the expectation and argument will be that you can always get your ass shuttled to wherever you need to be.