They wouldn't but that's like saying computer manufacturers don't need the OS manufacturers anymore. They wouldn't necessarily have to have Uber but Uber providing the payment, route planning and logistics and someone else providing the vehicle seems like a pretty good match.

Though I'll admit the self driving vehicle delivery is probably another level of difficulty than Uber's current capability. But I suspect Uber and the car manufacturer may work on the self driving together.

Uber is positioned to be the platform for transportation as a service. In their ideal world no one would own a car. Owning a car, like a plane or boat, would be come a luxury item.

Possibly so they don't have to buy one themselves? Similar to Car2Go.