Personally I think it's important for the Void Elves and High Elves to have a home on Azeroth proper; Void Elves specifically need to feel like part of the world, and the best way to do it is to be literal about it. That's one of the big problems of Telogrus, besides being just, barren.
And island could be great, but I'd prefer to be a place with some significance/importance, and in that case I think Highborne ruins would be a nice bet, as they can draw from that legacy as an unifying point + it would mesh with making feel the world feel more alive and evolving.
Maybe the VE's raising some of Zin'Aszhari could work because of the connection the area now has to the Void thus allowing further study, or maybe they could reclaim Shandaral because Northrend could use some present lore relevance, plus the aesthetic of the zone slaps, and in Chronicles their habitants are depicted as "High Elves" even if they wouldn't be of the same group of Dath'remar.