What if DoD did not spawn any what-ifs?
"What if Jared never told everyone that there was a specific ATL of the ATL?" I think that one's been on the back of my mind since I was 12 or 13 (I think that part of DoD came out in '06?) - years before I actually made an account here.
On the subject of the other possible direction that DoD could have taken, I actually think that the version we got played to DoD's narrative better than the other possibility would have. To my mind at least, the main narrative theme explored in DoD (distinct from AH themes) was a combination of "road to hell/best of good intentions" and the old "all it takes for evil to prevail in this world is for enough good men to do nothing". This was of course the main theme in the Draka series, which if memory serves was the initial inspiration for DoD, 'plausible Draka'. I think that a world in which the "good guys" ruin each other better represents this than one in which the narrative focus is on North America, where the fairly straightforward dystopia of total American victory is bad, but doesn't have quite the same sense of tragedy as it was not the (direct) result of good people failing, but bad people succeeding.
The *US had plenty interesting about it from an academic perspective in DoD with the exploration of industrial slavery and the incorporation of Anglo and Latin cultures in the Americas being probably the two biggest, with plenty of secondary features being present as well. From a narrative perspective however I always found the US a little less interesting compared to the other nations, as they did seem to just serve as straight up villains in the overall story. That's not to say that all Americans or American actions were actually villainous, but "as a character", if a country could be described as such, the US was not particular complicated.
The other nations however, in particular in Europe, seemed far more interesting in their character and actions. Britain, France, Germany, and Russia were all to varying degrees flawed, but fundamentally were not bad countries, at least by the standards of the time. They all shared democratic values to varying degrees, pursued essentially egalitarian in theory if not necessary in practice policies, and at times opposed genuine evil where they found it (usually in the Americas). In other words, they all roughly corresponded to the Western Allies of our WW2 in their character, nations we tend to associate with being on the side of "good", at least when compared to the sheer horror of the Axis Powers - or the *USA.
As such, I think that the Great War's focus being on Europe and not North America is more compelling. For people from a world where the democratic powers all found themselves on one side, a cursory glance at DoD's Europe would suggest that there was no cause for war, and that these nations would work together to defeat the US. Watching then these countries destroy each other while the US takes advantage of their distraction to conquer South America is more than a little heartbreaking. The aftermath is equally upsetting. Germany and Russia are largely friendless, having killed most of their potential allies and partners while alienating the rest (Australia's antagonism with Germany and Russia in very is unfortunate, given that it is the most direct opponent of the US after 1906). The fate of the British Empire is particularly bleak, being ultimately defeated not by the Americans, but by their own blunders and former allies. New England's betrayal of Britain is a great example of this. It is telling I think that arguably the best chapters and writing in the timeline occur in the end game of the war in Europe, despite this being principally a timeline about North America.
If the ATL had been written instead, I don't think this aspect of the story would have been lost, but I do think it would have been a little muted. Up until the end of the North American War the main narrative thrust had been the competition between the US and New England/Britain/Canada. This largely faded into the background after the North American War, but here it would absolutely still be centre stage. The battle in North America would certainly have been interesting to read. In particular I have often thought a chapter depicting the Black Fox running amok in Maryland or Virginia early in the war freeing slaves and humiliating the Americans would have been great, with the subsequent defeat there being equally compelling (depressing). Ultimately though given that the outcome would never have been in doubt what we would be seeing is good people trying to do good but failing against insurmountable odds, not good people failing to even try and do good at all. We still would have seen a version of this occur in Europe, from an AH perspective the difference is perhaps cosmetic at best, but I think there would be a distinct change in tone due to the focus on North America. For me personally, I prefer the tone of the world in which the focus is on those who may have done better than on those who intended to do bad.
Part of what sets DoD apart from most of works on this site, and indeed the whole genre is the combination of a well researched and well written AH with a clear and compelling narrative. We knew from very early in the story that something terrible would happen to Britain, that the US would succeed in maintaining slavery, and that the world the ATL history books were being written in was a troubled and unhappy one. It's rare for AH to have literary themes, but so enjoyable when it is pulled off like this.