I suspect Apple will replicate what they are already doing in Brazil, where Foxconn locally built a factory to manufacture specific Apple products to the local market.

Note two things: 1. I suspect this would be a Foxconn factory, not Apple (note how Tim Cook says "we'll be working with people"); 2. The total investment of the Foxconn factory in Brazil was 5 times bigger, so I suspect that Apple's $100m would cover only a fraction of the total investment required to build a factory in the US.

Regardless, that's good news for the American worker.