Jim Crow was inevitable so long as the Bourbon Democrats were preserved in some property and allowed to stay in the United States. Jim Crow, the elite response to the post-Original Klan multiracial populism of the late 19th century South, was geared not just to segregation and the recreation of Calhounian white solidarity, but to ensuring that poor blacks and poor whites, sharecroppers all, were essentially prevented from voting or participating in political life.
But if the United States does what it just -- exiling or executing every last Confederate officer or major official, and all the major planter sonsofbitches -- then suddenly the South is without an elite. Sure, the place would be dominated by Yankee capital, but a new political class would have to be created, and I doubt that, in the absence of the planters, this new class would resort to such extremes in preserving their own control over the South.
Some white solidarity is, as a feature of American life, inevitable; it was the planters and the Southron rich, beaten but not broken, who won the peace, and who restored the particular forms of Calhounian Southron solidarity that have never been replicated in the North.