This is a big, complex issue and one I am sure has nothing to do with design, altruism or nationalist pride.
The Macmini is probably the most copied to outright ripped off form factor in small consumer electronics packaging. I am working on an article exactly on this topic, including about 27 unique examples of gross design copy, maybe Core is interested in publishing it??? So, there may be some self preservation defense in bringing the manufacturing back to America.
However, along with Moses’ 10 commandments, Watergate’s Deep Throat “Follow the money” is an absolute business commandment. Apple is in a lot of trouble over financial accounting using a complex web of offshore subsidiary’s and accounts to evade all possible American taxes, meanwhile insulting the American taxpayer pointing out how much they do pay. No political arguments attempted here, it’s a complex and multivariate issue of fact regarding their and similar companies’ tax payment vs obtuse tax evasion, and current American administration tax revenue debate.
Along with ‘follow the money’, somewhere in there is probably the real reason to locate some manufacturing within America. Unfortunately, we need a tax guru to comment on scheme’s, programs and deferrals available to local manufacturers to properly assess Apple’s local manufacturing ploy.
As well, for sure there is a program within Apple to drop Samsung as a component supplier, it’s what corporate enemies do. There may be some obscure negotiations with American located or to be located chip manufacturers, probably in consort with local state governments and there will be local manufacturing and job quota demands.
Here’s another obscure possible reason, albeit probably more remote. At a conference I enjoyed a presenter’s talk on product pricing. He had lengthy analysis on cost driver’s stating that product pricing must allow for 10-11% of product shipped from China not reaching end destination: a combination of spoilage, piracy, damage, inventory mistakes. If Apple has lower margin’s on a given product line, finding a way to reduce that 10% cost may have a result in innovative ways to source local manufacture. Couple that with some intensely aggressive local tax program leverage, and you have an interesting announcement from Apple on “in-sourcing”.