Yep.
The northern dominated congress passed a resolution explicitly saying they were not fighting over slavery.
The Lincoln administration offered and the Northern dominated Congress passed with the necessary 2/3rds supermajority, the Corwin amendment which would have expressly protected slavery. This would have been irrevocable without the consent of the then 15 slaveholding states. It would have taken 45 states voting for a new amendment to overturn it and 45+15=60 which is 10 more states than are even in the country today. ie it would have been effectively irrevocable.
Everybody understood that. The Southern states could have had slavery forever if only they had been willing to return and face the high tariffs and unequal federal government expenditures.
They weren’t. They turned down the Corwin Amendment. Case closed.
Balderdash. The U.S. Supreme Court (sooner or later) would have issued a sane and Constitutional ruling which would have abolished Slavery and Involuntary Servitude throughout the entire United States and its territories—in stark contrast to the morally reprehensible, logically twisted, and patently unconstitutional Dred Scott decision.
Alternately or additionally, a Constitutional Amendment closely resembling the 13th Amendment would have eventually been ratified—starting with the North, but eventually with widespread support in both the South and the West—and the "Wheels of Progress" would cause America's "Original Sin" to inexorably fade into a shameful but distant memory...