The trouble with thinking in terms of blocs is that they don't solve the foundational economic problem: who is the sin-eater who is trusted and willing to run the deficits so that everyone else can run surpluses? Without a clear answer, you just have the same question repeated within and between blocs, so the same beggar-thy-neighbor incentives that exist without blocs exist within and between blocs, so the fighting continues within and between blocs until the question is answered. Blocs don't solve the problem at all.