Ya those should be kept as factions with their own Renown systems. For the PDK, a high renown would get ya either the Hippogryph or the Amethyst Dragon as a mount.
Odyssey of the Dragonlords has a legit subclass option for Paladins to get a Dragon buddy. So, there your refluffed PDK with an Amethyst Dragon mount proxy.
I have to look into my physical copy of the wonderful 3pp book Legacy of The Dragon and see what Breath Weapon type the Lung Half-Dragon got. Could use that for the reflavoured Spirit Dragonborn Breath Weapon type.
Goodness these books can not get any here FASTER!
Oh wait: Drow.
Ya can't have evil Drow WITHOUT the OPTION to play as a good one for all the Drizzt fans so that's gonna be my serious guess:
Dhampir, Drow, Aaracokra, Tabaxi, Kuo-Toa, Myconoids, Goblins, Changelings.
I wouldn't be opposed to them releasing a DM screen variant using the combined cover images. But it is neat that both the alt covers and the 2024 DM screen BOTH utilize a mural type theme.
Hmmm I wonder which seven species will appear in The dlc.
So far we have Dhampir. Hmmm, Aaracokra and Tabaxi? (If that's Themberchaud the cartoon gang is fighting, then Birbs and Cat people make sense due to them appearing in the movie and JARNATHAN!!)
Let's see...Kuo-Toa and Myconoids(BG3)...
Easy to reflavour the Dragonborn to include a Spirit Dragon option.
Does anybody know what element a Spirit Dragon breath weapon is?
Also, I really like the horns and how they almost have an antler like look. And the white chin on it's face gives of the "image" of a white beard.
Kara-Tur, you say? And they just released a (at the moment) Japan only module with pre-gens hailing from Kara-Tur as well. Which they may see if they can do a global release.
Hmmmmmm.....strokes non-existent beard
More details on the dlc(except the third one for now)
https://www.dndbeyond.com/posts/2032-everything-you-need-to-know-about-the-new
Looks like Astarion's Hunger dlc includes 18 more feats and 3 vampiric backgrounds.