1. Much higher body count with repeating firearms, imagine the South or both sides using Henry Rifles or Winchester '66 as their *standard issue!*
2. Slavery is not the primary issue until the middle of the war, it is a byproduct of the issue of state's rights
3. South will have more industry and railways, this might facilitate trade
4. Southerners have more time to prepare
5. Wild card: Grant may well drink himself to death before the war
1. Well, who is more likely to be armed with repeating rifles, the industrialized north, or the agrarian south? And this is probably actually a boon for the north, because they can afford much higher casualty rates than the south.
2. I don't even want to touch this; whatever I say will set off a chain reaction. But basically, someone will bring up the slavery issue at some point. It doesn't matter why the war is fought, but it will come to the fore.
3. 1 word: Why? Does the rich southern aristocrats having their way for 8 more years mean more industry? No. All the immigration, railroad construction, and industrialization is in the north. That is the main reason TL-191 could never happen.
4. The thoughts of an average southernor: Oh, this is just what I wanted!! 8 Years to prepare for the inevitable to happen, and for me to leave a union which has been practically run by my region since day 1, and which I feel closly connected enough to to consider myself American for most of the conflict.
5. Grant is over-rated. His greatest virtue was his willingness to keep fighting past massive casualties. There were other generals. And Lee will be gone, and with him many of his commanders. And to elaborate on Johnrankin's point, Lee only got command in 1862, bcause his commander was injured. So Lee, who is far more valuable to the CSA than Grant is to the USA, is out of the picture.