AFAIK the Wisconsin plant isn't going to happen. Even with the outrageous incentives, it will be more expensive than China. Because it isn't simple 'price of math of man hours in China <= price of man hours in America + savings in tariffs".
Set aside for a second the loss in margins due to absence of substantial ecosystem of parts and other manufacturing companies. The worker situation and protection in US would be a lot greater, which means 'less' productivity. So that man hour equation is a lot more complicated. That is unless a large scale automation of testing/validation effort kicks in. Again the technicians for those machines will be double or triple digit more expensive in the US (the rate at which income growth with skill rises in US is much higher - like most developed countries).
That deal, in the first place, was made possible because of multitude of reasons:
1. Foxconn saving their butt in case a horrible trade war happens between US and China, where the rumours were floating since way back before the tariffs actually came in effect last year (ref: Youtube video of Trump saying China, China, China)
2. According to Point 1, if China-US trade wars do hurt their business, fish for US tax incentives for minimal damage. Insurance.
3. The local Wisconsin representatives trying to win over voter base saying they will win jobs. These are the guys that screwed up. Just look at the scale of those incentives.
But we can see today, a trade war won't happen, atleast at the scale that will warrant an immediate start of manufacturing at the Wisconsin plant. This is because Trump and Xi know trade wars kill GDP, and GDP, with all its flaws is still the media's image of the long term economic growth.
> Is it that you're trying to route Chinese-made products through some minor step in India or Vietnam in order to say "no these really came from India/Vietnam, the tariff doesn't apply" and maintain capacity?
Possibly. India doesn't have the ecosystem for manufacturing many parts. So it might be the final step of assembly. Because the tariffs will be for phones, not for parts of phones. Though Indian government isn't stupid (I hope) enough to get the short end of that stick.