China's manufacturing sector is only 3% bigger than the US.
What disappeared were the unskilled jobs, and they are never coming back, because they are rapidly becoming obsolete.
Once upon a time almost everyone worked in agriculture. Now it's about 3%, and that 3% produces more food than ever. Expect the same thing to happen to manufacturing.
It may turn out that the time window in which a developing country could ride the outsourcing train to prosperity was actually only a few decades wide.
This. To get a job, the new requirement is to be able to do something that a robot can't do. And robots are improving rapidly.
Just like steam shovels put ditch diggers out of work, and spreadsheets put human calculators out of work, robots are putting factory workers out of work. As their dexterity and visual abilities improve, and their cost decreases, they'll start taking over other jobs: picking crops, washing dishes and cars, laying bricks, etc.
The big question, for which I don't have an answer, is whose problem it is when workers' skills become obsolete.
For example, did you know the staff at MacDonald's "manufactures" burgers?
As a reality check, how many people do you know who work in manufacturing?
BTW the only reason manufacturing is coming back is because the jobs are completely disappearing from it due to robotics and automation. From wikipedia "Employment in manufacturing ... its lowest since July 1950".
How many people do a thing should never be a measure, unless you don't care about inefficiency.