That's what's happening now, isn't it? "Blue" states are paying in more so "red" states can pay in less?
I suspect it isn't only because of the relative poverty of "red" states. Rather, it's an unavoidable compromise among states with different political preferences. The reason that "red" states will agree to greater entitlement spending than their voters prefer is because they are bribed to do so. The reason "blue" states will agree to the bribery is because it helps them fulfill their voters' preferences.
If decentralization ends this cooperative arrangement, it won't be a disaster. "Red" states will have to reorganize their spending priorities. "Blue" states will have a little more money to spend on whatever. Life will go on, but just a bit differently in South Dakota than in Oregon.