This is my thinking as well. If you can manufacture cars you can make them cheaper than anyone could ever buy them. So, if I'm a car company, I'm buying someone (or building in house, whichever looks more likely to succeed; hell maybe even both!) who can handle making the cars drive themselves.

Then you have two businesses; you manufacture cars to sell to people and you have a service arm that handles an Uber / Taxi like service with driverless cars.