I’ve watched this happen in a couple of German communities, and the after-effects of an American troop withdrawal has all kinds of consequences in a German community that go beyond the jobs lost.
Huge numbers of buildings are vacated, operational expenses that funded numerous local businesses are gone, mixed German-American families are left in German communities with no more “America” to hold on to, American schools are closed, social mixers that familiarize cultures are ended, and infrastructure created is no longer needed.
It’s been handled in other places, but it truly is a huge disruption for a decade at a minimum.
World War II did cause a bit of a disruption here in the USA, too.
The vacuum left in my former city has been filled by immigrants. The blight is sad to see- you are right, maybe in decades there will be recovery, but it is not the same place I grew up in.
It happened a dozen times in Japan from the 1950s through the 80s.