I consider Deadlands to be one of the best RPGs from the 1990s, and from the beginning I disliked the continued existence of the CSA. I can swallow a lot of aburdities including magic, weird science, and god-like beings from another dimension that feed on our fears, but I could not buy into the premise that the CSA was still around by 1876. And, honestly, the “cold war” between the USA and CSA never really featured in any game of Deadlands I ran. There are tons of wild west adventures you can have without any need for the CSA to be in existence. But yeah, they changed it because the game as originally envisioned played into the whole Lost Cause myth as they CSA abandoned slavery by 1876.