The cotton gin was patented in 1794 -- 5 years after the Constitution, and while the Founders were all alive (and many of them were reaping the benefits of slavery).
There was plenty of time for your mythical "death of slavery" to occur in the intervening 67 years, but the historical facts are quite the opposite: demand for slaves grew as King Cotton asserted its hold on the Southern economy.
Lincoln had little or nothing to do with the sectional rivalries that led to the Civil War. The sectional rivalry was fed by a Southern desire for the expansion of slavery into new territories -- and a northern desire to prevent it.
Whatever the economic sins of the north, it was the South that seceded over slavery. Don't take my word for it -- they said so themselves.
As the gentlemen of Mississippi so elequently stated,
This has been hashed to death here and elsewhere and we are never going to agree or see eye to eye on this.
I'll take Lincoln's own words over yours:
"My policy sought only to collect the Revenue (a 40 percent federal sales tax on imports to Southern States under the Morrill Tariff Act of 1861)." - Lincoln's First Message to the U.S. Congress, penned July 4, 1861."I have no purpose, directly or in-directly, to interfere with the institution of slavery in the States where it exists. I believe I have no lawful right to do so, and I have no inclination to do so," - Abraham Lincoln, March 4, 1861"Whereas an insurrection against the Government of the United States has broken out and the laws of the United States for the collection of the revenue cannot be effectually executed therein." - Abraham Lincoln, war declaration April 15th, 1861Taxation on slaves, Dredd-Scott and the intrusion of Federal power and oversight led to the decision of Southern states to cite the 10th Amendment and withdraw from the Union, and THAT - THAT RIGHT THERE is what directly led to war. Lincoln raised an army for one purpose: to force the Southern states back into the Union and capitulate to demands from Washington.
Slavery was only made an issue of cause for the war to bolster Lincoln's sagging support for the war in the North. Most of the locals in the South agreed with secession because it saw Washington as intruding upon their rights and saw the war as an issue of self-defense against tyranny of the state.
Slavery was a sin we paid for in blood - but it was not the cause of the war. Daring to defy the Feds and leaving the Union was the impetus for war.