Maybe panasonic will tech transfer battery tech aren't they also a big partner of Tesla?
I doubt Tasla will spend the money to build the supply chain, at least not in the short term. For the rest of the world, China and Germany would have the capacity to handle, plus with the downturn in sales thanks to the AOE damage from Trump, meeting demand wouldn’t be an issue at all.
That just leaves the raw material and refining that need to happen to supply the US gigafactory, since they can’t get the material from China anymore, India would be the next best option, get the refined material at the cheapest rate possible and leave the slag to the Indians to deal with.
Most importantly, I doubt Tasla has that much spare capital to invest into a completely new supply chain and it wouldn’t make any business sense to invest such an amount at such a volatile time other than to solve the most immediate of problems.