In the long run, I doubt that the Union can hold on to the former CSA. Trying to absorb a country which has been independent for eighty-something years, and has based its national identity on said independence, is not going to go well. The Union has enough trouble with Canada and the Mormons, both of which have much smaller populations.I could see this for the Republic of Texas. I doubt that the Union would allow any of the rest of the former CSA to break away ever again, Texas got lucky that it got to maintain its independence . I could see a (or several) War(s) between Texas and Mexico in the Cold War years. Maybe the Germans or Brazilians (who look to be becoming the leader of South America) prop up a Third Mexican Empire after the (Third/Fourth?) Mexican republic falls into Civil War. This Third Empire might seek to restore Tejas triggering a Brushfire War when Berlin makes it clear that direct American Interference would lead to Germany getting involved.