Assuming preservation of a federal govt that covers the continent coast to coast

Assuming preservation of a federal govt that covers the continent coast to coast (and better, from the isthmus of panama to the arctic), and the devolution of powers to the states resulting in restoration of regional sovereignty in internal affairs, there is no reason we cannot survive almost indefinitely. However, without that centralization the principle value of the territory – a giant island compared to eurasia – then I don’t see survival but balkanization.