The American populace won't ever take the jobs at the pay required for building the products in America to be viable for businesses.

The products would be more expensive, which less consumers would be able to afford, meaning even less demand.

American companies are also likely to start heavily looking at using robots or other devices to help with building and the tooling required because that is the only way to drive costs down, but that requires an up front investment that is difficult to justify to the shareholder when it's easier to ship it overseas.