First, thanks for doing some math, any math. Seriously. We'd have better outcomes if people did. In full disclosure, my numbers are SWAG, it all varies hugely according to location.
Second, thing in 'Doing the Math" is to start with some realistic numbers. Let's start with the '50,000'. The New York State Hudson Valley ( let's stay relatively close to Pennsylvania ) has long been a high tech manufacturing center for decades, but even recently there have been fab facilities constructed and expanded - take glance through those facilities, and you can compare the employment counts of LCD plants around the world also. Maybe, on the outside, a thousand workers at this facility on a permanent basis. In the global supply chain, the facilities operate according to various compromises of scale according to the products and markets, across all the major firms, whether it's Samsung, Phillips, Sony, etc. The facilities are even purposely designed so that the production lines can be readily decommissioned and relocated - even for things as large as aircraft ( http://www.aerogo.com/industri...
), all you need is a extremely flat floor, which is why companies favorite subsidy is the roads, lot, buildings, education training etc. that they can't move. The vast number ( Zipf's law ) of the 1000 employees are Electrical and Electronic Equipment Assemblers or equivalent ( Note that the TOTAL number of these folks in the US Semiconductor and Other Electronic Component Manufacturing industry is 41180 ( allied, maybe triple that), which gives another triangulation on the 50,000 figure for one plant. For now, I am just using Fermi estimation ( explained in XKCD's https://what-if.xkcd.com/84/
), and consider orders of magnitude. Definitely not 5, not 50, very highly automated 500, 5000 is a bit large, but certainly not 50,000. The wage is easier, mean Pennsylvania( 13,000 ) is about $35,640 annual.
Say the state or local government ( not certain how Penn allocates those responsibilities) has to pick up the tab for road construction in proximity to the plant ( Construct a new 2-lane undivided road – about $2 million to $3 million per mile in rural areas, about $3 million to $5 million in urban areas, ARBTA ). Then sewer, increased water supply, etc. It gets interesting when the government issues bonds to fund these for the companies, essentially a hidden form of taxation. Since there will be a howl from existing companies who will now be competing with Foxconn for the available labor pool, the state usually sets up a training program for those unemployed (10 instructors with burden), which alone would equal $600,000 - approx equal to the $600,000 from 5000 employees ( your calc mentioned 50,000 generating $6 Million ). ( BTW, 2015-16 Pennsylvania DOT's motor license fund total was budgeted at $4.37 billion, less PASP. $170 million around here doesn't even buy a mile of freeway, Fermi test on Wikipedia).
On my look, we are going to see a shift back to the US for simple reason that the China Sea is going to heat up considerably in the near future, and you may actually have 50,000 Foxconn Executives and higher management working as assemblers in Pennsylvania while they draw on their Swiss bank accounts.
HELP WANTED: Parking lot attendant, fluent in Mandarin and Cantonese, MS in EE
... nobody local, guess we'll need some visas