Julius Caesar said it succinctly, “Divide and conquer.” Whether it is Great Britain, the United States, or any other nation or group of nations, it is easier to conquer them when they are in a divided state than it is to conquer them when they are united in fact, purpose, and spirit.
It is one thing for the people of Scotland to strive for a greater voice in self determination while united in purpose and spirit, and it is another to strive for a greater voice in self determination while divided in geography, economy, purpose, and spirit.
Right now, the US is not united in purpose and spirit.
Divide and thrive could be more the case with the USA, though...
If we carved off the cesspools called cities, and let them govern themselves, and the rest of us govern ourselves,
I have no doubt who would thrive and who would flounder.