And lose all that cheap labor? China knows that threat would be empty.
Robotic manufacturing will eliminate most of those jobs within 10-20 years. China already has half a billion people with no jobs available to them, that are pretending to work as subsistence farmers currently. The labor will always be cheap, it's the politics that will become extremely expensive. Apple should get started on moving off of that labor while they still have the vast financial capabilities to do so.