Who would join SC if anybody? How long would it take the US to win? How would it be seen in pop culture? would it end slavery?
Regarding slavery, I think it may depend on the circumstances, but if Nat Turner's rebellion still happens, slavery probably won't end, totally, in the short term.....regardless, though, I do think the Yankees will still become much more suspicious of Southern regionalist rumblings, sooner than OTL; whereas it took until stuff like Dred Scott to really see a lot of pushback, it could be coming on as soon as 1840, perhaps, ITTL. And in this case, I can also see, possibly, a new Missouri Compromise being drawn up, during that same decade, in which slavery is automatically abolished in any new territory acquired from Mexico, save maybe Texas, and perhaps even Missouri itself as well(even if on a gradual basis). No doubt this would anger many of the hardcore rightists in the south, but after getting their asses stomped, and if especially by Old Hickory, they're not liable to try outright secession again.
As for who might join S.C., Mississippi is certainly quite the possibility, as is Georgia. Alabama might, certainly, but it might come at the cost of some of it's northern counties(historically, during OTL's Civil War, there was a not terribly insignificant amount of sympathy for the Union in many of those places, although perhaps not on the level of East Tennessee and western North Carolina)