One thought on production plans. It looks like Tesla will export battery packs, motors, inverters and other powertrain components from GF1 to GF3 between September-19 and March-20. This is when they plan to ramp up in-house production at GF3.
This means Tesla will have an excess 3k per week battery packs and powertrains in GF1 in March 2020. These components are all likely shared with Model Y, so these components could be diverted to Model Y in GF1 in March 2020 - so for these components the S curve production ramp for Y could already be done by March 2020.
We know Tesla managed to ramp general assembly in a tent over just a few weeks in Fremont, we also know Tesla plan to advance from construction complete at GF3 in May to body, paint and assembly production by September - suggesting just c.4 months to install these production lines. So it is possible Tesla could start installing equivalent lines at GF1 in December 2019 and already be at 3k per week Y production by March 2020. Of course, suppliers are likely to be much slower moving and these will be the real bottleneck. So it all comes down to how soon suppliers get moving.
In summary, I think Tesla's internal (best case & unlikely) target could well be 3k Ys produced per week at GF1 or Fremont by March 2020. But they may not have to decide exactly where until November 2019.