>>>>>What if, after everything sugars off, that MSP becomes the international hub for everything westbound, DTW the international hub for everything eastbound, and ATL the international hub for everything southbound?

I think that would mean that a majority of potential customers would have three-segment international connections (and would choose to fly an airline that didn't) unless each hub also offered direct flights to every U.S. destination--it makes more sense the other way around: international connections each direction from each hub, and regional feeds to the hub.