With thunder rumbling outside, as some small, New England-sized thunderstorms wander across the vastness of the Texas countryside, the atmosphere would seem to be just right to contemplate your vision of a potential separation.
First, any separation would be founded squarely on solid cultural factors that Blue and Red America divide quite sharply on, not merely on reactionary Southern resistance to "Northernness" -- which is shorthand for selfish brio and casual abusiveness justified by its idolators and beneficiaries as "impartiality" and "businesslike impersonality" -- one size screws all.
The values dichotomy is real and deep. First, any departure by the South would condemn the rest of the country to an endless procession of liberal presidents and Congresses, which would have dramatic consequences for the recovering economies of the former Rust Belt states, which are trying to come back as a combination of service and high-technology economies. It isn't just a matter of speechways and folkways. It's a difference in how people are perceived. Beyond stating that obvious difference, I'll leave its elaboration to various people, who, smarter than I, have attempted to mine the Red-Blue Divide for intelligible information and insight.
Sectional and regional differences, remembered loyalties and differences in voting patterns, would, I think, leave the Midwest and Mountain West with the Union. They vote Red (notice how the writer of the original article cleverly avoided assigning Gore the "Red" position, which would have been a little too telling), i.e., often with Republicans....but they would be left behind by the South to become perpetual junior partners of the industrial North, and its helpless thralls. The future of the West and Southwest under such a separation would be imponderable, but I would say as an aside -- I think I've referred to it above -- that any separation of the South from the Union would likely occur as a result of a successful partition of the Southwest by Mexico sponsoring Mexican-American "Aztlanists" to the United Nations and various anti-American world powers, setting the stage for a second collision of the Old Southwest (viz. the western states of the Confederacy) with the new.
Your argument that the differences between North and South are thin and vanishing is itself thin and wishful. You need only read the Christopher Caldwell article in the June, 1998, Atlantic Monthly about "The Southern Captivity of the GOP", which I think I've referred to before, to see the regional differences usefully sharpened for purposes of arguing that the Bushites must be allowed to abandon the GOP's Nixonian Southern (and conservative) base in order to pursue "tent-widening" strategies that avoid the shrinking horror with which voters in Blue America would otherwise inevitably come to regard the GOP. Which is a hell of a long, and usefully circuitous and diverting, way of saying that the Republican Party needs to retrogress to a New York-dominated "me-too" strategy like that employed by the Rockefeller Republicans of 50 years ago, and for the same reasons. But there I leave Caldwell, satisfied that his horror of Southernness presents fairly a regional division that means a lot more than you think it does.
What made the Southern agrarianism of the 1930s so appealing to many was the contrast between the agrarian South and the industrial North at a time when industrial capitalism was in trouble. A rural, agricultural society is always socially or culturally conservative, even when it elects or is led by radicals, liberals or socialists. The ties of family and religion are too strong to be denied.
The idea of the heartless North and the warm South with its strong emotional ties may have appeal as a general rule, but it also has a lot of problems. How much more personalized and non-instrumental were relations in North Carolina textile factory towns than in New England mill towns? Was Birmingham really less economically driven than Pittsburgh? If the argument is that Birmingham was always an anomaly in the South, one has to deal with sharecropping, convict labor and other conditions of the day. The post-bellum may have been more open to the ties of community and extended families than the North at the same time. But it was not less exploitative. Rural Vermont or Iowa may have been more Yankee, but were they really more profit-driven or materialistic than rural Mississippi or Arkansas?
And what does this have to do with the "post-industrial" America of today? Does that old industrial-agricultural parallel still exist? Pittsburgh is no longer what it once was. "Detroit" is as likely to be in Tennessee today as in Michigan. Were such "Blue Zone" centers as San Francisco, Seattle, Portland, Minneapolis, ever given over to "dark, satanic mills?" The characteristic of the deep blue zone is an indifference to smokestack industries and industrial regimentation. Today, Vermont and Maine, Iowa and Wisconsin may be more reliably Democrat in presidential campaigns than West Virginia, Pennsylvania, or even Michigan.
If a rural society cannot help but be culturally conservative, even under a radical rulership, a post-industrial society, driven by information, sensation and design, tends towards cultural radicalism, even under conservative political overlordship. The sophisticated urban types are likely to be much the same wherever you go, in Houston or Atlanta as much as New York or Los Angeles.
Of course they would only be a small part of any Southern nation, but their numbers would increase. Rural areas look to industry and commerce to provide work for those who can't support themselves on agriculture. As basic industries become less profitable in the developed world the temptation is to turn to high-tech, style-driven enterprises. That temptation is to embrace innovation, rather than stability or rootedness.
The trauma of many countries has been whether to accept this trend or try to avoid it by adopting or preserving socialist or centralized or social managerial economies. Such collectivist alternatives have generally failed and been rejected. One can't imagine they'd be very popular with those who think secession is about liberty. So the acceptance and enthusiasm for the innovation- and sensation-driven post-industrial economy continues and grows and with it, a movement away from traditional social and cultural norms.
Oppositions between South and North, Cavalier and Yankee will always endure. But what's made of them isn't constant, no more than oppositions between Quebec and English Canada or England and Ireland or Fleming and Walloon. In defense of their interests Quebec went from being collectivist under Trudeau to free market under Mulroney to whatever they are now. Flemish speaking Belgians went from being the poor exploited victims of rich French-speaking Walloons to being the richer, post-industrial adversaries of the Walloons who were still chained to coal, iron, textiles and steel. Protestant Ulster looked down on backward, priest-ridden Ireland. Today, swinging Dublin and even provincial Irish cities pity tired Belfast with its eternal war, decaying shipyards and unemployed.
Traditionalist, obscurantist Eire embraced modernity two or three generations after independence. They still are Irish, but "Irish" doesn't mean the same thing. Stodgy, snobbish, stagnant Ontario went all out for modernism, progressivism and multiculturalism. Clericalist, traditionalist Quebec also rushed into consumerism and individualism. Toronto or Ottawa still isn't New York or Detroit. Montreal and Quebec still aren't Toronto or Vancouver, but the differences and the cities and the cultures they represent aren't what they used to be.
My point is 1) you can't assume that the South will remain true to its rural roots -- it could embrace affluence and modernism or post-modernism with a vengeance -- and 2) one can't expect "Southernism" to be something fixed eternally and immutably. It only looks that way because of the North-South political opposition within a united country.
One can imagine southern "caring" and "familialism" and "traditionalism" being given a collectivist tinge once the Yankee is banished. Look at the change in the US over the last seventy years. The Democratic South and West which supported Roosevelt and the New Deal and their public works projects became the most Republican regions of the country. The Yankee individualist and high capitalist Northeast is now the most Democratic region. What is to prevent another reversal of polarities from happening?
The "it's ours" argument that applied to slavery and segregation may be applied to a more comprehensive welfare system than the cold North provides. If the country does break up, the Northern fragments will likely beat the South to single-payer health care, but you can never tell.
I think you are right about a secession of "Aztlan" acting as a trigger to future secessions. It's hard to see what else could play this role. If one region goes, others may follow. It should be noted that the same might happen in Mexico. The proposed "Republica del Norte" has little use for the Aztec South. So it's a question of what Chicano nationalism is really about.
But if the United States break up, it's a major blow to the "American" model on such things as abortion, capital punishment, gun control, homosexual marriage, national health care and other issues. The pressure to adopt European standards becomes much greater when there's no longer a superpower standing up to it. But it does stand to reason that after we topple the Saudis the next step is to undo our own country.