I guess as Jesus alludes to in the first post, it could have implications for separatist movements elsewhere in the world. And there does seem to have been a growth in Separatism, worldwide, in recent years. 

Are there any serious separatist movements in the U.S.? 

This sort of thing can have snowballing effects in a world with heterogenous populations living on the same land. Call it "pride of tribe" if you wish.

Kind of what would happen if a large rogue planet suddenly entered our solar system: every other planet would feel it and perhaps have their orbits slightly disturbed.

Check out what is going on in eastern Ukraine with pro-Russian communities.

In Canada it seems that first Nations are increasingly winning land claim trials which give them almost sovereign powers over large territories. Some Crees are wanting to separate from Quebec as I write this.

And it's theoretically conceivable that such things can still happen in the US for purely economic reasons. Given the extreme political polarization in the US what WOULD happen today if 5-6 southern states suddenly came forward with a plan to secede and form their own union? Instant military action or negotiation?

Anyway, the Scottish situation is interesting because it's an example of a "civilized" process with a clear question. Normally this sort of process fuels military tensions and at least a bit of sabre rattling.