If their largest selling item (PMAGs) become illegal to manufacture, they have to move at least that part of the business.
I don't think it would work that way. Lots of companies produce things that they can't sell to the public. I'm reasonably certain CO would find a way to let them make the PMAG's. They would just have to ship all of them out of the state. Except the ones that the CO police wanted... of course.