So please indulge me with you answer; as an American, how does this affect you?
Let me see, what is Europe's banking center and arguably the financial capital of the world wakes up to find an influential member-state of its parent country gone. Her banks move south as there is a run on said bank.
Just as that problem arises the parent country has to consider debt allocation (after all, Scotland's is in debt with the rest of the UK, how much of the debt should they take on and by what criteria? And just what do we do with the pound anyhow? Should the Scots keep the pound? Will there be a Scottish pound and a South Britannic pound? Who controls the monetary policy? The fiscal policy? And what of laws? Those also provide a certain degree of predictability in the market and with gangsters like Salmond who knows what would happen to that end.
In short, ripples would occur that would spread throughout the global economy.
But let's put aside the economic argument for a moment. "Okay Des." You might say. "Those are just short term ripples and the liberation of a people is more important than your pocketbook."
All well and good, I suppose. Let us consider then the topic of secession shall we?
Europe and America tend to follow each other rather closely when it comes to socio-political trends. Many historians say that if you want to see where America will be in seven to fourteen years, look across the Atlantic. Primarily to mother England.
With the advent of technology too that gap in timing is shortening. You may remember that the big hubub over DOMA actually followed the big hubub over gay marriage in the UK. This timing is not merely coincidental.
So Scotland secedes to create their own little socialist utopia. Well, there are states that would like to do the same thing here in the US of A. Vermont and Oregon have little rumblings now and then. If you include conservative dissatisfaction look no farther than Texas. It is not unthinkable that we may have similar referendums here.
If you can't see it happening, consider the fact that the British didn't see Scotland coming so close to leaving the fold.
Let us not discount the fact either that a successfully separate Scotland may embolden certain factions.
So yes, if you care about or are at least interested in the continued union of the United States, Scotland should be of some importance to you.
Editorially, it hits close to home for me because I have family across the pond who will be more directly affected by this than I am (Spanish in-laws living near the Basque lands if you are curious).
"But Des." You say, "I don't care about any of these things! The economy! Pfffft. Secession? Pfffft. I just want to be safe and surely five million people leaving the United Kingdom is no big deal."
And you may be right! But then, you run the serious risk of being wrong as well. Scotland leaves, it makes the UK look weak. UK looking weak emboldens people who happen to hate democracy. Now if this happened twenty years ago, I would say, okey doke. At this geopolitical moment though, you can bet your bottom dollar it would be of importance and motivate some not so nice people to do more not so nice things to English speaking people regardless of national origin.
Then there is that little matter of nuclear weapons. The UK's nukes, nuclear submarines, and submarine pens are all up in Scotland. Sure, the Scots do not want nukes, but the question is where they will be held, how will they be transported, where will they go?
To make things more interesting, the next available storage space is in London. I have no doubt the UK's military will be able to hold them safely,
As a general rule, any time there is a question of moving nukes everyone on planet earth has a concern.
There are a couple other points I could make here, but I think those three shall suffice to say that we all have a stake in this. Mind you I was ambivalent about the prospect of Scottish independence and, more than anything, fascinated because one day the events that transpired will have a degree of influence on my life as an American taxpayer.