I doubt many people see Genghis Khan as a hero. And I doubt all that many people see Caesar as one, although perhaps he's complex.
Actually, I have a rather positive impression of Genghis Khan. He was way ahead of his time, and only slaughtered millions because because the Mongols couldn't leave heavy garrisons to keep conquered populations in check. OK, it doesn't really sound that good, but I still admire him quite a lot.
I doubt that Hitler's reputation will ever be rehabilitated. This is because, while people may be prepared to forgive the crimes of ancient or medieval warlords on the grounds of historical context, Hitler didn't have such an excuse. Arguably he was no worse a warmonger than Napoleon, but Napoleon didn't attempt to exterminate an entire ethnicity on industrial lines. That is a horror that will retain its power to appall no matter how many generations pass.
Are you suggesting that genocide is "over?" I think that the modern world, with its anonymous, depersonalized form of warfare, will make it ever easier to kill and wipe out whole peoples. China needs strategic space and defensible boundaries in central Asia? So long, Tibetans! Russia needs to secure Baltic territory permanently? Latvians, say hello to your
new home. Auschwitz was made possible partly because of the efficiency and industrialization of killing in gas chambers. To them, eliminating Jews or undesirables wasn't much different than how we regard locking people up in mental hospitals or prisons today- they're brutal but "necessary." People simply don't care. It wouldn't matter even if every last philosopher in the world agreed that fetuses had full human rights; they don't talk, or think, or wake, so they simply aren't human to the vast majority voters. I think that the Holocaust won't be looked upon as too peculiar or out of place in future history textbooks, any more than Caesar's slaughter of the Belgae tribes is today.
As a possible comparison, consider Crassus' crucifixion of six thousand slaves along the Appian Way. That was a very long time ago, in an age when such barbarity was not uncommon, but I think there's still something peculiarly horrible about it even when we learn about it today. Crassus isn't "up there" with Hitler because he's not as well known or as historically significant, but I think it's a good example of an ancient brutality that still appalls us now.
I agree that
Hitler's genocide will always be looked on as uniquely horrific, given that it was not a political struggle. As Muhammad Dajani pointed out, the concept of a "Jewish-Nazi peace process" is piquantly absurd. Most genocide takes place because of political circumstances or as collateral from massive scale-warfare (the Mongols would be a good example- if one man in a village resisted, they all died).
The Holocaust is orders of magnitude worse than that, not to mention far more culturally significant (I mean so widely known and branded into our cultural memories and awareness).
No, the Holocaust isn't really "branded in our cultural memories" so deeply that it won't ever fade. In the direct post-war era I've gotten the impression that the Holocaust was pretty traumatic for Germany itself. It was, I believe, taboo in public discourse, and Holocaust studies never really got off the ground until the
Destruction of the European Jews was published in 1961. Seriously, if the Holocaust is so easily subject to political winds, what makes it distinct from the Armenian genocide, which still isn't universally accepted as fact because of Turkey's importance and prominence in the Middle East?