Current model assumes one car per person. That's because only one person can drive a car.
How many self driving Teslas could be needed to meet transportation demand for just the US. A lot more than a million.
If Tesla can actually deliver a mass produced self driving car while everyone is still figuring out how to make electric cars with good mileage then they become the next Toyota. Just like Apple became the next Nokia.
Corolla sales are above 1.2M per year.
The 900k number is Model 3 and Model Y.