You assume that the manufacturing base was destroyed. Part of it was not destroyed, it was abandoned as uncompetitive. It was simply not required.
You assume that the world stands still and everything remains the same. The world of trade is dynamic, not static. Change is constant, the only constant.
The fact is the world did not stand still. The world entered the quest for better life and competed. Parts of American industry were bloated and over regulated and could not compete in the manufacture of many things. The work was lost to those who can make things at a lower price.
America still has a strong manufacturing base. That base is dependent on brains and skills and technology. The combination of those elements means that the labor required to produce is less than before. That change is called productivity increase. We make more with less labor.
BS, our highly productive and PROFITABLE manufacturing base was shipped overseas to increase profits a few more pennies on the dollar. We are so screwed now and weak in heavy industries that a major war would cause us to start to hurl nukes almost from the outset because we cannot fight a war of attrition(any more). I can't and will not stand to listen to free traitors blather on on how we deserved what we got, count your blood money in quiet and STFU. The blood of future patriots is on your hands, curse you all.