Tesla intends capacity will be 500,000 cars p.a., =1m vehicles p.a. including US. Most car plants are 200-300k p.a. China car sales: 28 million in 2017 (biggest market).
“Tesla said the first cars would roll off the Shanghai production line about two years after construction begins on the factory. Production will ramp up to 500,000 vehicles a year about two to three years later, roughly matching the planned output at Tesla’s current Fremont, California factory.”
The Shanghai city government seems supportive.
Good luck. The world needs this kind of vehicle-change, and bilateral between US and China, to work.