Leaked documents show Tesla plans to build small Model Y SUV at Gigafactory 1 by the end of 2020 and another production line in the China Gigafactory a few months later. It will have a third-row seat. The timeline is outdated. It seems that the actual timelines will be delayed by months to as much as two years based upon ongoing Model 3 production challenges.
The worst of the Model 3 Production problems are over. Elon Musk and Tesla have learned a lot about the right mix of automation. A second and third try at starting production of a new car that is still based upon the Model 3 platform should be much smoother and faster than the Model 3 production ramp. However, there is no proof that Tesla has worked out how to cleanly ramp to 7000 cars per week. They have many lessons to get to 4500 cars per week.
Tesla had planned to ramp up both factories' Model Y production lines to 7,000 cars per week in Nevada and 5,000 cars per week in China by early 2021. The current Model 3 production is having difficulties reaching and maintaining 5000 cars per week. The current goal is to reach 7000 and sustain Model 3 cars per week in the next month or two.