“Which would instantly destroy the US economy.”
On the contrary, it would destroy the Russian and Chinese economies, putting them back to the economies they had before 1978. Without the United States and Europe to cheat on their foreign exchange rates, their economies will shrivel up and die, while the return of U.S. manufacturing jobs will cause the U.S. economy to boom again. The booming employment then greatly boosts income taxes and defrays the national debt not already confiscated due to war with the parties holding the debt instruments.
Manufacturing is NEVER coming back to the US, not as long as there are 3rd world countries filled with billions of people willing to work for almost nothing.