None of the 50 states currently have a standing military. What if those corporate interests don't take no for an answer, and decide to hire private military contractors to conquer it by force? With the collapse of the U.S. military, there'll be plenty of mercenaries available. What if, after consolidating their power in their new former U.S. holdings, they decide that they want more and push for expansion? At that point, the corporations can have their own professional armies, made up of former U.S. citizens, fight against the remaining "independent" states.
I'm not saying your initial premise is wrong, but you haven't fully looked at the consequences of releasing ~43 incredibly weak nations into the world with no treaties or alliances protecting them. It guarantees conflict. You'd have maybe seven states masquerading as the "real United States," and complete chaos.