I believe at the first sign of weakness they would jump on the chance to gain some control over the US.
A serious internal fight would surely diminish our ability to stop a foreign country or countries from gaining control over the US economically and/or militarily.
If there was a revolution in the US, the vast majority of foreign countries would stay home and cry.
Like it or not, (I like) America holds that much sway in the world. Our economy hiccups, and Irish potato farmers will make runs on their local banks. Ah, globalization. Imagine if there was a revolution here.
Those countries that can stand on their own (barely) would do everything they can to preserve our union - for us, not them. Many nations out there would love to fill the power vacuum that we'd leave behind, should we go to war with ourselves, but they all know that it's one super-powerful vacuum that only one country in the world can fill right now - us.
Who will buy all that crappy anime out of Japan?
Who will buy all that crappy home decor out of China?
Who will be driving those cute little Volkswagons?
In return, where will the rest of the world turn to when they need to get pick up some McDonald's on their way to go see a dubbed version of "Pirates of the Carribean" while scratching their butts through their Levi's jeans?
Arrogant? Hell yes.
Oh, and it's much easier to hate on Jean-Jaques from across the Atlantic, than to hate on your neighbor.