Yes, Fitzhugh wanted to enslave poor whites, and no, he wasn't widely read. But when you say "slavery wasn't going anywhere" with whites, that was PRECISELY the logical end point of Lincoln's argument, because if something was morally wrong in New York it was also morally wrong in North Carolina, and if it was morally right in South Carolina, it was morally right in Wisconsin. You can say "state's rights," but ultimately evil is evil. Southerners well remembered the days of "indentured servitude" by whites (many historians think that the end of white indentures was directly tied to the racialization of slavery), and if it happened once, logical whites might think, what's to keep it from happening again?
In the South, he was -- someone quoted sales figures to show it. The planter class read him, but his ideas didn't gain currency.
But when you say "slavery wasn't going anywhere" with whites,...
No, I didn't say that -- be careful. I said the idea of enslaving whites didn't go anywhere. Southerners used race as a firewall, to keep slavery from touching them the way it frequently reached free blacks, who were always at risk of being "claimed" by someone -- sometimes, they were sold into slavery by e.g. the State of Illinois, if they violated Illinois's black code by attempting to settle there.
......that was PRECISELY the logical end point of Lincoln's argument, because if something was morally wrong in New York it was also morally wrong in North Carolina, and if it was morally right in South Carolina, it was morally right in Wisconsin.
Abolitionists were the minority in holding that moral view, and to put it bluntly, many of them "believed" that for operational purposes, rather than sincerely. The moral argument -- like all moral arguments -- was turned out as a political prostitute the minute it was picked up by politicians claiming to act under its color. Southerners had the entire Bible on their side: if Deuternomy laid down rules for slave and master, where did the Yankee Abolitionists, to whom the accusation came so cheaply, get off saying that slavery was immoral?. Inconsistent with small-r republican principles, perhaps, but that doesn't rise to the level of a moral indictment by the Almighty, which big-A Abolitionists said it was. Southerners had only to crack open their Old Testaments for a little comparison study, to refute the claim.
You can say "state's rights," but ultimately evil is evil.
It isn't evil just because you say so. What, is smoking "evil" because you don't like it? Does that give you the right to damn to hell anyone who disagrees with you? Get a grip.
Northerners who wanted to abolish slavery were in the position of petitioners. They wanted to make a major change in society that would overhaul everything from received morality (yes, that's right) to the Constitution. They achieved it by yelling, bulling their necks, instigating a war, and imposing their values by force and violence. How "moral" is that? A million dead for "morality"? Funny how "The Battle Hymn of the Republic" doesn't mention anything about the cost, or about burning out half the country so you can feel smug in church.
Proposing a better policy is always a good idea, but if you haven't the right to impose it on others, it is incumbent on you to accept the fact. Moral arrogance doesn't entitle you to bash your neighbor's brains ina, call it "justice," and treat his children as if they had the mark of Cain. But that is exactly what the Abolitionists did, led by Lincoln, and that is the position you are taking now.
It's especially obvious, when the victors then sink themselves in the kind of moral corruption that attended the Gilded Age. Congressmen who'd called for Jeff Davis's neck on a plate and for burning out the planters, happily signed on for the Credit Mobilier. They were hypocrites, and their moral invective against the South has to be seen through that corrective prism.