Americans can do without allies? America has gained its allies for many years, and you can lose a few days. If country is not your ally, is a potential enemy. You seriously think that without allies America can be great?
The US must accommodate the considerations from its allies. But this shouldn't mean that it should give preference to foreigners over its own citizens. How can you justify GM and Ford closing their factories in the US, and opening new ones in Mexico?
It's a competitive job market. Why are you talking only about Mexico? You probably forgot about the refineries? They will close as well. What to do? In addition to these places come the Japanese.In the end, not just jobs and capital leaving America.