A company can go non union if it wants to.So people will replace union workers if there isn't a strike, but not if there is? The union wouldn't go on strike if the company started replacing them?
They can stay or move, it matters not.
I made the Statement that in most citys like ft wayne it would be difficult to hire the 4500 employees necessary to run that plant.
Manufactors tend to build plants where they already have a workforce living nearby.