At appropriate saturation the number of cars being displaced by riders is significant, though I wonder what that is and how it trends over time.

If I was in college today, I might never consider buying a vehicle.

No. What happens is that roads keep becoming saturated until they are clogged with ride shares and the riders bail out when they realize they can walk faster. The equilibrium point creates complete havoc for everyone else and little productive work is actually done.

The roads are already clogged with cars. Does it matter if they are ride shares or not?

A saturated Uber-model ride share market is one where an empty car is seconds away whenever you need one. Idle ride shares matter a lot.

Or it could be a model where there is always a car with a ride share available.

I mean could it be the Uber Go model is the best win-win for the customers, Uber and the drivers?