I believe it would have eventually happened over some issue...maybe abortion or gay marriage? Heck, there are people clamoring for secession today because they don't like the results of the election! I would have to believe that it wouldn't have resulted in the death of 2% of our population though.
Well: there is no way to prove what's only speculation one way or the other, obviously. All we DO know is that secession and war did happen, and they happened in the context of, among other things, a vicious sectarian dispute over the morality of chattel slavery.
The economic dimensions can't be overlooked. But then that makes for a full circle since slavery was part and parcel of the southern economy. Southerners supported the institution with increasing fervency in the 1830's not only because of reading too much Walter Scott or native racism but also because slavery had become very much in their economic interest.
I think far too much of the history of the 1850's has to overlooked to dismiss the central salience of slavery as the cause for the war. Charles Sumner wasn't beaten sensesless on the senate floor over internal improvements. Dred Scott and the Lincoln Douglas debates weren't argued over tariffs. John Brown did not attack Harpers Ferry over the homestead act. Bleeding Kansas wasn't fought out over the question of a central bank.
But I take on board the irony of your comment: "Heck, there are people clamoring for secession today because they don't like the results of the election!" That is, in esence, exactly what South Carolina and its six Deep South sister states did in December 1860 to February 1861 (the four border states, you could argue, seceded more immediately over Lincoln's call for 75,000 volunteers after Fort Sumter to suppress the Confederacy). And I say that with as much dislike as Dr. Williams for the insanity perpetrated daily by the leviathan of Big Government.
secession is their RIGHT!
i, for one, will go to the new international border on secession day to wish them "FAREWELL!", "BYE,BYE!" & "ADIOS!"
free dixie,sw