>When we consider that there is a significant amount of people that currently cannot drive that will now be able to drive with the introduction of self driving cars, such as children and the elderly,

Also, I'd expect the average number of people per car to decrease. I could even see the average dipping below one. Just think of things like sending your empty car to the vet, to pick up the dog. Or sending an empty car to Walmart to have them fill your grocery order. Or people who will have their empty car circle around instead of paying for parking (or because there are no parking spots available). And think about how no-passenger cars aren't really going to care too much if they are stuck in traffic.