It's very obvious that 
is circling the drain now, but clearly this didn't just happen in a vacuum. It must've started crumbling at some point... but when?
Some people might say it started after 9/11, others might say it goes back to the Raegan administration. A few might even say it started after losing the Vietnam War, or when they went off the gold standard. Or maybe even earlier...
What do you think? 
I don't think they have anywhere close enough military might and political will to keep a balkanizing US together. You could have a repeat of the Eight Nation Alliance where an alliance of multiple nations decide to hold the US together, but that's just balkinzation in another name since those alliance of nations will most likely partition the US into multiple parts with each nation administrating a particular partition. This was what happened to parts of the Ottoman Empire after WWI and Germany after WWII.
Partitioning would work I think, but the main point is the US breaking up independently is not really on the table for the rest of the world. It’s too unstable for other nations to do nothing. Imagine 4 or 5 new Israel’s all threatening to annihilate not only one another, but also any one of old Americas enemies? It’s not going to happen imho