“Slavery was dying (even in the south) well before the Civil War” Between 1850 and 1860, the slave population in the United States increased by 749,000 individuals.
“Slaves were illegal to import in America for decades” The American flagged ship Clotilda delivered between 120 and 160 slaves from Africa to the Mobile Bay area of Alabama in July 1860.
“Only a small percentage of Southern whites even owned slaves.” A true statement on the surface. Another way of putting that was 34% of families in the States that seceded owned slaves. Around 383,000 people owned slaves according to the 1860 census, most resident in the South.
“Slavery was becoming an uneconomic model due to industrialization, standardization and vast increases in productivity, especially in agriculture” Slavery was a very viable economic model as long as Cotton was King. As for manufacturing, it even used slaves in the South. The work force at Tredegar Iron Works in Richmond, VA (largest industrial operation in the South)was 50% slaves. They were not only laborers, but skilled machinists, foundry men, and mill wrights. The same situation existed in almost all Southern manufacturing operation. As long as the South was the main supplier of cotton to the world, slavery would have continued to rule the economic landscape of the South.
“It would have died naturally. Without the need for nearly a million Americans to die.” Probably, but it could have well lasted into the early 20th century. The first workable cotton picking machine was not invented until 1920s. As long as fortunes were to be made growing cotton and tobacco, slavery would have continued to exist in the South.
Interesting thing, that 1860 Census. There were over 450,000 slaves in Union states, who remained slaves until the passage of the 13th Amendment, unlike slaves in southern states who were freed at the end of the Civil War.
One of the most well known slave owners in SC history was William Elison. An ex slave who bought his freedom. There were many black men in the South who owned slaves. When the war broke out he sided with the CSA and his sons fought for the Confederacy.
https://historyengine.richmond.edu/episodes/view/6699