If that level of batteries was only for making 100 KWH cars then it would be 20 million cars per year. This would more likely be 10 million cars, one hundred thousand semi-trucks and storage products.
Elon said that Tesla is still a few months from being feature complete with self-driving. Feature complete self-driving means that you have a good chance of the human driver not being required to intervene from driving from one location to another across local streets, intersections and highways. There would need to be further improvements for the self-driving to get regulatory approval.
Autonomy will enable high volume and high margin business.
The Fremont, Berlin and Shanghai gigafactories will enable local production of model 3 and model Y.
The Plaid powertrain will come out later this year. Elon describes it as like-alien technology.