Deploying fully-autonomous road vehicles --- by which I mean vehicles that can drive themselves across a busy city with no human occupant, under any conditions the average human driver could handle, safely mingling with human-driven vehicles such as cars and bicycles --- seems tremendously difficult to me. I keep hearing optimistic timelines; surely they're either misleading about promised capabilities or they're wild fantasy. But I may be wrong.
Indeed, I hope I'm wrong. I don't like owning a car, and the sooner autonomous taxi services are cheaper and more convenient than car ownership for me --- and most other people --- the better. (Presumably this is Uber's vision.) This would have some interesting effects...
We'd need a lot less parking. We'd free up household driveways, garages and carports for conversion into gardens or residential space --- sounds great. Parking lots and garages would still be needed for the taxi fleet, but not in as many places. We could free up a lot of street parking for bicycle lanes, bus lanes, traffic lanes, and taxi pickup bays.
You could customize the vehicle for the journey. Taking a one-person trip a short distance? Rent a tiny one-person short-range vehicle. No need to drive a big vehicle around just because once in a while you need to carry six people. (One interesting question is how passenger density compares to buses and trains if everyone uses a journey-customized vehicle.) This would be great for uptake of electric vehicles. Hopefully large numbers of autonomous vehicles would make roads safer for tiny vehicles, as well as cyclists and pedestrians.
Often you have to drive from A to B instead of using another transport option just because later you'll need to drive somewhere else. Cheap taxis solve that problem, and make connecting to public transport easier for many people.
Making vehicular travel cheaper will encourage it, especially among people who can't currently drive. This is bad for congestion, but it's good for those people! Some of the above changes will help mitigate congestion, but we might need to finally tax these negative externalities.
I think economic forces, for once, are pushing in a good direction. If it becomes cheaper and more convenient to give up one's car, people will do it even if it causes a temporary increase in overall congestion. Once the majority of people are on board, policy changes like removing street parking and and congestion charges for people attached to their big vehicles become much easier.
A couple of standard fears arise in this scenario. The non-existence of computer security is a big problem; hackers will wreak extreme havoc. Also, it's important for the autonomous taxi fleet to be a competitive market; I don't want Uber or anyone else dominating. This is going to be tough since the network effects will be huge. I'm glad China is fighting hard against the Uber-opoly.