As much as I’d dream of this. If the blue states left, it would tank the red economy and make them pissy. They would then pull a Russia and try to force back those states. You’d then have old US being attacked by Mexico, Canada and New US. The other issue is that most of the weapons of mass destruction are currently residing mostly red states.

Since this side of the world would be in turmoil, I’d have to assume Russia and China would take advantage of that for their own gains.