Well, it's certainly going to be cheaper, but it's completely naive to believe it's simply "the cost today, less the cost of the driver". Driverless is a new paradigm.

For one single issue, look at the society we live in; who is going to clean the car when the inevitable happens? How will that even work? Or do you think people will happily jump in a dirty car?

So, while you do not pay the driver (who makes little anyway), there will be new costs.