Kinda sucks if they tie all Paladins to Silver Hand but these types of classes (Druid/Paladin/Warlock/Shaman) do kinda need a handwave to add them to more than one race. Unfortunately.
Well, if we take it as a case per case basis, it doesn’t make too much sense for there to many hardcore separations.
You got your base Void Elves who may or may not be accepting people who may or may not be turning Void-ish. (We REALLY need some lore for this…)
You got your Allerian Stronghold who make no sense to not be connected, one group being the troops of Alleria and the other being her students. And given their decades in Outland, they have a unique view of things and likely knowledge of the Void, and where likely there when Alleria took interest in it. Plus this is already my headcannon for their source of Warriors/Hunters/Rogues…
Stormwind High Elves who are, lets be honest, are basically holding hands and skipping down the sidewalk with Void Elves since their introduction. And are the likely source of High Elves entering the rift.
Quel’Lithien Lodge… They’re (Mostly) dead Jim. Only tie in that would make sense would be if the artifact that corrupted them turned out to be a Void Artifact and the Void Elves have a fix.
Silver Covenant are already a military organization with a few other races as members. I don’t see them merging one way or the other but I can see a few either becoming Void Elves (Summoner Nolric?) or they start accepting them as members/working with them on larger military endeavors.
Dalaran High Elves aren’t really their own group so much as Citizens of Dalaran (Raise your heads to the sky!) like Stormwind High Elves, so I can see it much the same.
Highvale are the least likely to be either joining the Void Elves or accepting them as members, given their use of light and isolationism. And aside from not liking Arcane are the most stereotypical High Elves. So barring them having a unique understanding of Light and Void and becoming the source of Void Elf Paladins or something I don’t see it changing.
So while I don’t see any group overwritten by the other, logically it makes a lot of sense for there to be a lot of intermingling between the groups. Given how similar their history and goals seem to be.
My 2c on the subject.