If you get down to it, Modern High Elves could be easily defined as a group of immigrants that broke of from their nation politically, who's culture now is being hybridized by their host's culture.
That would be a pretty unique take on elves as an immigrant story, which is basically a lot of their context by being thalassian elves on the alliance. Cultural syncretism, culture clash, reforging of tradition, there's a LOT blizzard could draw inspiration from.
IMO this approach would would for either High Elves or Half Elves, but regardless, there is already a whole set up to tell this story. Dalaran is already a multicultural city where we can see the hybridization of human and elven culture and its people, where the Silver Covenant was formed, who was called out by Elisande as "elves that diluted their bloodline with lesser races." There's so much potential for High Elven lore to actually be about that eroded identity.
I'd like High Elves to be playable, but a big reason of that is because I see a lot of potential on the place they have occupied on the alliance since WarII, there's so much unique history to them as a people in terms of experience that separates them from Blood Elves and Void Elves, an experience that could lead them to an interesting place.
I have to admit that I see more potential on the legacy of their heritage rather than who they are "now," so while I'd really like HE to be playable, I think that Half Elves actually would be the most interesting result of High Elf lore.
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Humans, gnomes, draenei, dwarves, all those SI:7 members that are already playable, except for the one goblin (on the alliance at least)
Yeah dude, that's really not the same than the group almost exclusively showcased to be comprised of High Elves (a non playable race)
And it's definitively Blizzard's fault that they gave this non playable faction more screen time than other groups. It wouldn't be the same issue of the SC was instead made of playable alliance races (it could have been humans and gnomes with some helves)