For the most part, they are currently unemployable -- uneducated (or under-educated), unmotivated and irresponsible, accepting of a lifestyle based on government handouts.
There needs to be a broad revolution in both education and welfare -- not to mention attitude -- in order for the current inhabitants to be productive members of society.
Thus, it isn't the departure of manufacturing that created this regrettable situation. Nor would the return of manufacturing solve it.
I agree with you, but then what? You have to be able to show an alternative.
You can't tell someone to "get a job" and then take all the jobs away.