Lets look at a few things regarding the slavery issue. The Souths main export was cotton purchased primarily by Great Britain. Slavery was outlawed in all British territories, so it stands to reason that in order to maintain good foreign relations with European partners, slavery would have likely died out in the South eventually even without a war.
I remember reading that any Southerner who owned 50 slaves was exempt from the draft. Most of the soldiers in the Confederate Army were to poor to own 5, let alone 50 slaves.