Alliance Nightborne

ah I see but you may not remember my point at that time, I wrote it could be an expansion based on “BC’s Azeroth regions” (Quel’Thalas, Azuremyst and new unpublished zones around Quel’Thalas like Zul’Aman Empire and new islands) while remaking on totally new maps with new scale, just like WoD did Draenor out of BC’s Outland. About the Horde flag over it … Now faction war is softening again, plus Quel’Thalas is arguably Horde and independent at the same time, it’s not that tied to the Horde when you look at the story.
Quel’Thalas once was lightly allied with the old Alliance, and some B Elves do think about these times.

Look, now they have Void Elves who are from Quel’Thalas too, and High Elves are becoming playable Horde-side as I foresaw some time ago

Zul’Aman Empire is of Troll interest. (All the more with frest troll options becoming playable soon too.)
Relics of the highborne can be of Night Elf and Nightborn interest. Maybe Second and Third War relics to interest Orcs and Humans+Undead.
If the expansion after SL brings us back on Azeroth that would still make a fair option.