And out in the boonies, some people will keep their personal cars, as it will take longer to get a ride.

Also, the average car size will shrink. Not only will we lose the driver's seat, but peak demand as people go to work may be met with even smaller one-seat cars.

You won't need a car that can handle your worst-case scenario for most of the time. Bigger cars will still be available, of course, because people do like to travel with their friends and family whenever possible.

All in all, it's a lot more likely that that most seats will be filled.