I think the clear winner would be those who control the food supply and most of the guns.
They lost last time. The south had a far greater proportion of its population armed and trained. It was about people and money. The blue states make a lot more money and they house a lot more people.
In the end though, who cares? If the red states want to secede I say let them. They seem to want a very different type of governance than I do so I say let them have it. They might be sad when they figure out what that actually means, but that's how people learn.