This is nonense.
(1) Tesla has already built a global supply chain and can simply reuse it. China's "made in China" content requirements which apply to Tesla are not really significant enough to change that. Tesla will continue importing certain parts to China, probably including their self-driving chip (making it at a second fab doesn't make sense to me)
(2) Tesla makes so many of their own parts that the main things they buy -- rolls of steel, rolls of aluminum, raw plastic pellets -- are commodities which are straightforward to line up.
(3) Many of their suppliers are, of course, already in China.
(4) They have been lining up this supply chain for the Shanghai Gigafactory since before the factory was approved, so they've had plenty of time.
Now, you have drawn the wrong conclusion. But there is a correct conclusion. Tesla will have to build a *lot* of factories inside that Shanghai factory:
-- metal casting (copying Lathrop in the US)
-- seat construction (copying the Page Ave. factory in the US)
-- pack construction (copying the Sparks Gigafactory)
-- and of course body, paint, and final assembly (copying Fremont)
It's substantially more than a duplication of Fremont. Much of this should be able to go in parallel, I should hope... but odds that *something* will hit a major delay are high.