I am not saying what I would or would not support, but a possible reality, based in part on the historical precedent of the breakup of the old Polish Republic which happened a few times in the 1600s and 1700s, then functionally sort of again in the 1900s.
My imagined scenario:
USA, Canada and Mexico functionally merge for a time, the "North American Union" with free travel between all states, sort of. But then the issue would not become one of immigration or migration of any worker class, but the major asset owning class. When the entire enchilada dumps in value due to lopsided trade deficits. International corporations will demand something for their dollars, foreign governments will demand something, so they will move to buy land.
Canadian land will be nearly worthless just by virtue of nobody wanting to freeze to death most of the year. I'll throw a quasi sci-fi twist into this one: Asian interests buy huge chunks of Canada, get their hands on HAARP and weather control weapons, and attempt to bring about "peaceful use" of the weapons to warm up the northern provinces, causing the unintended flooding of much of the pacific and Japan. Japan threatens war over it, wins in the International courts, and is given the Chinese holdings in Canada, which they begin moving large numbers of refugees to. Same with Indonesia, Phillippines and other Island nations. Canadians try to resist, but international public sentiment is against them, and in a major voter referrendum, the money and productivity brought by the Asians is a determining factor in letting them stay. The breakup of Canada into newly Asian owned provinces marks a beginning of the internationalized ownership of the NAU.
Europeans start asserting ownership in the Mexican mainland, Mexicans resist, citing their old constitutional restrictions against non-citizens owning land. Again, a voter referendum, and the majority which supports the NAU wins.
The USA gets hit by economic downturn and major weather disruptions, but the NAU keeps the economy going for another couple of decades. Again, foreign ownership of large tracts of land is the result of them calling in their ownership of US dollars in propping up the US government, thus, German military bases in Arizona are only a start, other nations establish their own autonomous zones, then demand their own internal security forces.
Patriotic organizations are manipulated by all parties involved to be against the NAU, but the end of the NAU would not mean the re-establishment of Old America, no, the reality of massive tracts of land owned by foreign countries which sometimes even go to war against each other means that when the NAU breaks up, the new maps are a checkerboard of autonomous zones, but Washington DC remains a capital in name only. The old US federal government would still exist, just as far as US troops and an expanded Marshall's service can reach.
Out of all of that, one of the most viable independent nations from an economic, strategic and military standpoint would be Alaska with chunks of western Canada. Mostly white, already involved with international trade, but with its own opposing internal political factions.
1: the "we got ours so fuck everyone else" crowd. Armed and isolationist enviro-nazis, led symbolically by Native Americans, but functionally by descendants of early settlers. They attack all development and want the Alaska nation to remain mostly wild and "unspoiled". They see an economy that can be sustainably small through controlled state owned exports. They make an alliance with old school communists in Russia in an attempt to fight off the oil cartels and Russian developers. Both them and their allies in Moscow lose to the political reality. Through a series of thinly disguised contract murders, their leadership are decimated and scattered into the wilderness by the Russian tycoons. They sympathizers can be found in every town and city while they continue to fight against immigration and development.
2: The patriot alliance; old line Republicans and new immigrants to Alaska, along with Canadian sympathizers. While an extremely powerful international lobby and economic force, and capable military force made up largely of leftover USA military assets abandoned in Alaska and purchased from failing independent states, they also suffer from infighting. The international intrigue tries to steer clear of conflict with the patriot alliance, buying off whichever factions appear to be up and coming, and quite often being forced to fund infighting among the factions. The Patriot Alliance being a loose coalition of unlikely political bedfellows spend most of their time at each other's throats, but when united, are responsible for the breakoff of Alaska from the NAU, and starts the cascade of breakaway movements from the NAU. A stated purpose of their original political leadership is that the breakaway republics would attempt to re-establish "Old America" with a capitol somewhere in Montana.
With the threat of the Patriot Alliance against the NAU and the Washington DC government, and heavy infiltration of Washington DC politics by PA agents and sympathizers, the Washington DC government invites international police and military forces to assert a presence in areas where the population is ripe for rebellion and joining of the PA. In some cases, they try to convince people to join the DC government and respect the NAU which is tongue and cheek referred to as the "Texas Government" and largely corporate ruled, in other cases, deportations to Alaska become common, however those joining the American Diaspora to the last frontier get there to find it a mess, and with political infighting common among the PA, with hard core resistance to everything being carried out by the small but highly competent and effective isolationist Alaskans. We will call them the "Call of the Wild" party. The COTW party then gains an underground support base among natives everywhere, from Alaska on down to southern Mexico.
The Texas government rules the NAU, and heavily armed trade convoys sporting the NAU flag and NAU mercenaries are quite often the safest and most reliable means of trade in an otherwise deteriorating US. While the DC government will use political pressure and limited force to bully taxes and financial support from the NAU, the NAU asserts its charter through a combination of treaty law and judges they own. They see themselves as the inheritors of Americas original "Manifest Destiny" doctrine. This time, spreading north and South.
At some point, in an attempt to re-unify the nation, and enhance the "National Identity" of the NAU, the Texas government constantly agitates for an invasionary war on South America, citing an official alliance between an aging Hugo Chavez and the Nuclear armed Persian Gulf Coalition.
We could really play this out even in scenario play to the point there are no more clear cut "good guys" or bad guys, but there is right and wrong, on the personal scale, and survivors, and entrepreneurs, and constant conflict, but personally, I think maybe actual functional Nationhood would not survive any of these major changes for a long time. The Ideals of the founding fathers, yeah, but in different forms depending on where you are and who you are in the whole checkerboard of autonomous zones.
