The civil war would have taken place. It was the divide over so many tarrifs and taxes, it wasnt about slavery.
As I pointed out earlier, if the southern States had not seceded, the Republicans would never have been able to enact their economic platform into law as the Democrats would have had solid control of the Senate. The tariff couldn't have gone up in 1861 without secession.
However, there is a small kernel of truth to what you say. Were it not for the economics of plantation slavery, the South would not have been as opposed to tariffs as it was. The economic system the South preferred, with the South specializing in slave labor production of agricultural commodities (as agriculture was and still is the economic area in which slave labor suffers the least disadvantage in comparison with free labor). High tariffs were disadvantageous to an economy dependent upon the use of slave labor to produce agricultural commodities for export. Southern opposition to tariffs was because they correctly saw them as negatively impacting slavery, not because of any high-minded devotion to free trade.
Exactly. The War was, in many ways, brought on by the South's fear that their economy, and, basically, their way of life, would be eradicated. And, of course, slavery was the corner stone of their economy.