If final assembly and all packaging is currently done overseas, and the majority of the customers are in North America, it certainly makes logistic and shipping cost sense to do final assembly here. The smaller components will still be made overseas but larger unwieldy parts like the curved stand for iMacs and displays can be made in the USA near the final assembly location. Should allow for a better JIT assembly line, less standing inventory (not that Apple has a problem with that), and the opportunity to ship less air overseas. With the tighter packaging on iPads, the laptops, and phones it makes less sense.
So, I’d imagine the iMacs and whatever the next gen Mac Pro might be (if they continue) would be good candidates for US fabrication and assembly.
Do they build the factory near the UPS or FedEx shipping centers?