Follow along with my thinking here.

If autonomous cars become a viable technology, which I believe they will.

Then you can expect to be able to have the car "drive" you to work with little or no supervision.

Why then would you need your car to stay downtown or at your work after it drops you off?

You could send it home.

If a car is expected to provide door to door service and then return to its starting point, couldn't it then provide someone else with ridership service, doesn't that imply a few things about our urban centers.

Would we need as many parking lots?  Would we need ANY parking lots?

Do the new autonomous cars replace buses?  bikes? 

Routine Maintenance:
Think about this.  Your car needs routine maintenance.  It messages you on your handheld at work.  Providing suggestions for service locations automatically researched for price and quality.  You choose one and away your car goes. 

You come out after work and you car drives up, beeps its cute little horn, all happy like, you hop in and away you go.

No more School Bus:
You've got a group of families, several kids.  Who needs a school bus.  Hop in the car kids, it'll drop you off at school.  It wouldn't allow them to open the door until they were there.  It'd be safer than YOU driving them to school.

Change:
It becomes a tool, an extension of our reach, an appendage.  It CHANGES the relationship between a person and a car.