Sure I agree in this scenario a lot of jobs will be made obsolete. I suppose self-driving cars will be cheap, but not free. That money goes to the owner of the car I'm guessing? Leasing self-driving cars to use as taxis has got to be big business.
You could get your self driving car to become a taxi and make money for you when you are not using it! I assume the traditional taxi market would become obsolete if you could do this with self driving cars.