Interesting analysis. I was more curious as to what foreign powers you think may become involved in one way or another.
Alaska might be a temptation for Russia, possibly China. I think China would definitely consider Gobbling up our Pacific holdings, including Hawaii. The eventual winner of CWII would make a lot of noise, but it would be a fait accompli. I think it’s safe to assume that a second civil war in America would progress less like the first and more like the conflicts in the Balkans or Rwanda, so the winner would likely be brutalized and thoroughly spent.
Hm, harder -- I'm not really up on my "rest of the countries of the world"... but I'll give an off-the-cuff analysis.
Individually, most countries would be hesitant to get involved because civil wars are typically bad juju [ie waste of resources] (think Bosnia) that provide little payoff and the difficulty of keeping the supply-lines across the ocean isn't negligible. So that leaves Mexico and Canada as the "most likelies" with Mexico likely trying to grab the southwest -- Canada is interesting, I don't think they'd get involved and might actually benefit from "war refugees"... then again, IIRC, they do have socialized medicine and they might think twice about burdening their system by accepting them.
Of the oversea foreign powers China is the likeliest to make a mad snatch at something -- they're signaling a lot of expansion-desire with the recent disagreement w/ Japan over those little islands, the incursions into India, and... one other thing that slips my mind, at the moment.
Russia might try to grab Alaska because it's mostly empty (undefended) and mostly cut off from the rest of the US... but the expansion-desire from China may keep that in check. (It wouldn't do to gain Alaska and lose a giant portion of their mainland holdings.)
Israel, England, and France are probably the only friendly foreign [oversea] powers that might send aid -- of course that's a double-edged blade, if it's military aid they'll back the FedGov and be "fighting on the wrong side" -- but I doubt that they'd get involved militarily (Israel especially, considering where they are and their situation they need their fighting-forces accessible, not half a planet away).
I think most of the EU wouldn't care, considering their own problems and how on-the-hook they are with debt. The UN, on the other hand, might be tempted to send in peacekeeping forces... and if that's the case it'll probably shake some FedGov loyalties. It might even spark more of the general population to get involved... after all, foreign troops subjugating your fellow citizen is far less tolerable than federal troops firing on people under questionable circumstance/orders.
The whole situation smells of a "damned if you do, damned if you don't" -- because if we don't have a civil war, then the fedgov really is all-powerful... and if we do we'll bleed, bleed, bleed. One of the things that it seems like, with the questionable Kabuki and recent actions in DC is that there's a bit of a script that goes like this: spark some violence, put it down QUICKLY, use that as an excuse to disarm the people, implement the more distasteful aspects of socialism and aristocracy (the governing elite being the new aristocracy) and burearchy (rule by bureaucrats).
A misstep [out of order] on any of those and the whole thing blows up in their faces.
Forgot Mexico. I think there would be a very strong chance of Mexican involvement along the border, either at the behest of 0 if still in office or of its own accord if CWII broke out under some future administration. They do have millions of national and ethnic loyalists already behind our lines.