I wouldn't be as dismissive of void elves as you @
Aldo Hawk (because the war campaign and incursions where they use the Void against the Zandalari and all, which hinted at some very interesting potential) but I'm pretty sure that the 8.3 story for Alleria was never meant to forshadow VE. For me, it was just all an opportunity to have a powerful Void user in the Alliance, the "balance" to the dark powers of the Banshee Queen.
I think I came back to finally play Legion already knowing what the AR would be and being extremely disappointed with the VE. They have grown on me but they'd need so much work and time dedicated to just them to be fleshed out that Blizzard won't ever give us that.
High Elves already had that fleshing out and more. They had potential locations (Dalaran or, my favorite, a new and imprived Quel'Danil Lodge becoming the start of a new HE city in the Hinterlands, linked to Aerie Peak, and now Stromgarde and thus Khaz Modan), a leader (Vereesa), a theme (the actual rejection of arcane dependence) and an army (the Silver Covenant).
But alas, they are still languishing in the strange zone where they appear en masse more often than any other race save Humans in the Alliance but are still not playable