Yeah that's what got me confused too. Then I realized:
All of the "supported" factions are ones that were outright squatted or squatted/disseminated amongst other armies and are outright unplayable in AoS
Not really, though? Warriors of chaos is still a big
AoS faction that has a bunch of overlap with the oldhammer faction. And Dark Elves are basically unplayable in
AoS. A couple of their units exist in one
AoS faction, and a couple in another, but 'Dark Elves' in general aren't any more playable in
AoS than 'Orcs & Goblins' or 'Empire' are. Heck, Beastmen are practically the same army with the same units and the same models in
AoS and Oldhammer.
Edit: That being said, isn't the Red Duke active at this time?
Nope. He had already returned from the dead, reached the end of his second campaign, and fled into the wilderness upon discovering that he had slain his own descendant in his madness, all before the start of the Von Carstein wars. He's out there somewhere, haunting the forests of the old world like a wild animal, but barring retcons he doesn't properly appear again until the End Times.
If the Old World timeline progresses forward instead of staying locked in place, then we'll get to the False Grail event and the collapse of Mousillon, which features an incursion of nurgle daemons and the city being overrun by undead after the nurgle incursion passes, so could be used as an excuse to reintroduce both chaos daemons and vamp counts as a faction.
We're explicitly leading up to the Seige of Praag, which is pretty much the opposite of chaos 'at an ebb', so I'd expect chaos daemons proper to be back by that point. Maliketh also launched a major invasion into Ulthuan right before the Great Chaos War, so there's a contemporary reason to bring back dark elves as well.
Also, I was wrong about the high elves, they're present in the old world at this time, Having signed a major trade deal with Marienburg and even established an enclave in the city. They shouldn't really have armies marching around the old world, so they easily could have been left out, but they're not /not/ around.
What I would have loved to see in the Old World is a focus on specific narrative campaigns instead of a set period of time. Like initial Old World release is 'Old World: the Great Chaos War', and it focuses exclusively on the factions involved in that war with extended narrative campaign rules. Then those armies are set aside and we get 'Old World: The Vampire Wars' or 'Old World: Age of Vengeance' or 'Old World: the False Grail' or 'Old World: Wars of Sand and Snow, and so on, each book taking a close look at some particular period of old world history but with no particular commitment to stay in the same time period or progressing in any particular chronological order from one release to another.
These would be highly focused narrative campaign books, each with like 2 to 4 specific armies or army variants. All would use the same core rules, so you could take your evil Brettonian army of Duke Maldred from the False Grail book and play it in a pick up game against somebody else's Dark Elf raiding fleet from the Age of Vengeance book, with periodic pdf updates making points and balance adjustments to past armies to keep them up to date with whatever the newest release.
That kind of structure would still start more or less the same as we're seeing now, with pdf 'tide you over' rules for old factions with no particular commitment to support them fully in the near term, but then instead of starting at a point when nothing in particular was happening and slowly building up to a major event they would just dive into an exciting major event like the Seige of Praag right away with a Narrative Campaign book and detailed rules for just the 2-4 specific factions present for that battle and an extended 'made to order' run of just those factions old models plus new models for the specific named heroes leading those factions in that event. Let that be the Old World for 6 months or even a year, then the next Old World release jumps to some other exciting major event with detailed rules, made to order releases, and a couple new models for 2 to 4 other specific factions, along with a 'balance' update released online for those armies not involved in the new narrative book.
...
But whatever. They'll do what they'll do.
