In debates about the American Civil War and its causes, one often hears the argument advanced that the efforts of the Northern abolitionists were unnecessary as slave labor was already on the way out, owing to its declining profitability. I've always found this argument preposterous on its face, but in the course of reading Götz Aly's "Hitler's Beneficiaries", I am struck anew by the utter mendacity of such an assertion: not only did the Nazi regime make slavery pay, but it paid on a truly colossal scale, something on the order of $100-150 billion in the space of a handful of years. If slavery could be made to pay so handsomely in 1941-1945, and in a Germany whose economy was already far more knowledge-intensive than the American South would be until perhaps the 1980s*, why are we supposed to believe that slavery would be abolished today without a war to force its abolition? Why would the South have been willing to go to war to preserve a soon-to-be obsolete institution in the first place?
Human slavery is and likely always will be profitable, at least until reality catches up with Blade Runner and artificial sentient humanoids can be made to do what men, women and children in chains would have (and even that would simply be replacing one type of slavery with another). Optimists might like to believe otherwise, and nothing will stop neo-confederate apologists masquerading as "libertarians" from continuing to make stupid arguments to the contrary, but the viability of slavery is something that will not change in the foreseeable future.
*To be perfectly candid, it isn't even clear that this is true today, considered objectively. 1930s Germany was a creative and innovative powerhouse on a scale that the American South just doesn't seem to be.
PS: A little searching turns up this paper on the economics of slavery in the antebellum South. As expected - and in contrast to the rubbish to be found on "Lew Rockwell" and similar sites - the paper gives every reason to believe that slavery would have continued to thrive had the American Civil War been averted.