There's plenty of people with vocational (i.e. blue collar) skills here in the US. More than enough to even fill the hundreds of thousands of jobs companies like Foxconn and others employ to make the iPhone.
It ultimately comes to down to a question of public servitude. IMO, yes, Apple should have an obligation to employ as much US blue collar labor in the manufacturing of its products for all of the incentives and perks that it- as a company- enjoys being based in the US, lobbying, and taking advantage of US tax laws.
And despite selling less iPhones, it's being reported that Apple just broke the record for profit margins in the smartphone market last quarter (91%). So there is plenty of 'room' to employ US blue collar labor if they're breaking the bank with so much profit.
Except those jobs are going to be filled by robots, not from our blue collar workforce.