The multiplier effect—and there's a lot of data on this from an auto assembly plant—is quite large. If you have an assembly plant with 3,000 employees, you're probably employing 6,000 supply jobs, and then you're looking at the jobs that are created when you're building the schools, and the Tim Hortons, and construction, and all that type of stuff.
As assembly plants leave, you will lose those other jobs.