Upstate New York is not what I would call a thriving economy. That's why it loses population as downstate gains population. Illegals go where the work is.
It doing fine enough, and there's lots of legal immigrants in the area which I don't consider a problem. The point is, we don't need illegals to get by. The toilets are getting cleaned, the beds made and the hamburgers served.
As far as the population loss... maybe that's because it gets cold up here. :)