While I could see the rest of the CSA crumbling and gradually getting reabsorbed into the USA, I can’t see that with Texas. All Texas had to do was last until the first big oil boom at the turn of the century, and that would be all she wrote. I’d think they’d go after some territory in Mexico, and today we’d have the USA, a Texas somewhat larger than it is now, and Mexico, somewhat smaller than it is now.
Which brings up the interesting idea that the USA might not get into WWI, since it wouldn’t have much of a border with Mexico, although the Zimmermann letter could then be about the Germans offering Texas an alliance to take New Orleans, which would certainly be a prize worth fighting for. And then the war does happen, except our troops are fighting Texas instead of Germany, and in Europe as a result the whole thing results in a stalemate, while over here maybe Texas gets reconquered? Hmm…
The Zimmerman telegram was a big deal at the time, but the sinking of the Lusitania and ongoing German unrestricted submarine warfare was bigger. I think the U.S. would still have fought in Europe on much the same scale.
The problem with Lee serving for the Union (as a dramatic convention) is that the war would have presumably been much shorter if the North’s power was directed by Lee’s mind. Shorter and less dramatic makes for boring stories. 
Sailboat
Not necessarily. The aftermath, especially in this example, can be far more interesting. If the CSA wins, what will politics be like in North America? If the North wins quickly and easily, how will the South be treated? How will Reconstruction and civil rights change?
If the Confederacy had been smashed quick and early (a very unlikely prospect IMHO), there would almost certainly have been less progress for African-Americans.
Ironically, even though slavery was the avowed issue over which the South had seceeded, the Union didn’t dare make the war a crusade against slavery, for fear of alienating the northern public. The Emancipation Proclamation itself was legally a limited war meaure, and was only issued after sufficient progress had been made that it wouldn’t look like an act of desperation. The real movement against slavery, the Thirteenth Amendment, only came about when total victory was in sight and emancipation was recognized as a way of removing the incentive for further rebellion. Even then issuing full civil rights to African-Americans was in part a political strategy- every freedman was a guaranteed Republican vote.
If the war had ended in 1863 or earlier, it might have been considered necessary to guarantee slavery in the existing slave states as a concession to mollify the South. It took four years of war and the total crushing of the South for the political capital for nationwide emancipation to emerge.
Lumpy, I completely agree. This is often overlooked in considering the political backdrop to the war.