Not sure why you got downvoted. While I think the number of cars sold will decrease, I don't think it will be by very much. The biggest problem is that most people go to work and go home at roughly the same times during the day, so realistically you can't have more than maybe 2-3 people sharing a car if they're both employed. Yes, some fraction of a city's residents work non-standard hours, but the majority are on something close to a 9-5 schedule.
Also keep in mind that while the number of cars sold might go down, it's also fairly likely that the margin on each car will go up, and the total number of miles driven will go up as well. Basically when you take the unwanted part of driving out of the equation (sitting in traffic wasting time) and don't need driver attention anymore, you can start adding all kinds of value-add features to vehicles like giant in-vehicle displays or massage chairs. And if you can do whatever you want while on the road, longer commutes aren't so bad, so it's easy to put more miles on a car in a year, which means more replacement parts, service visits, etc. over time.
The market will no doubt change significantly, but existing OEMs are by no means going to be excluded entirely.
Also keep in mind that while the number of cars sold might go down, it's also fairly likely that the margin on each car will go up, and the total number of miles driven will go up as well. Basically when you take the unwanted part of driving out of the equation (sitting in traffic wasting time) and don't need driver attention anymore, you can start adding all kinds of value-add features to vehicles like giant in-vehicle displays or massage chairs. And if you can do whatever you want while on the road, longer commutes aren't so bad, so it's easy to put more miles on a car in a year, which means more replacement parts, service visits, etc. over time.
The market will no doubt change significantly, but existing OEMs are by no means going to be excluded entirely.