Of course, in the event, they'd have had to wait out the entire industrial revolution -- which is more like what they were seceding from: dehumanization of citizens (to a status very much nearer that of slaves than that of 18th-century citizen-farmers), time-clocks, humiliation by corner-office Napoleons and industrial tin gods. They saw it all coming, armed and liberated from State and regional control by the business faction in control in DC, and they wanted out.
But that isn't what we're arguing.
The fact was, the South seceded, and the argument is over whether they were within their rights so to do.
Then there's all the other stuff about whether Southerners really are unpleasant racist knuckledraggers in Hitchcockian-caricature baggy clothes, snaggly teeth, three-day beards, and slouch hats.
Some southern states purported to secede. They had no right to do so, and this was confirmed in Texas v White: "The act which consummated her admission into the Union was something more than a compact; it was the incorporation of a new member into the political body. And it was final."