It was Softsong who noted that Lanesh looks like he is wearing tattered Scryer clothing, and if he’s a former Scryer he’s an Outland High Elf presumably, because his blue eyes indicate he wasn’t w BEs during the time we would have gotten them as a side effect to stuff.
So if he’s a Outland HE he could be one of the Shattrath refugees we see or Allerian Elves.
And when asked Danuser on twitter said there is a story behind him & they are aware he has blue eyes the story just hasn’t been told yet. So the speculation / request for that story to be told is just as valid as Alliance HE fans who want to see some integration of any Elves in the rift.
The fact we have the blue eyed customization again allows for player agency for that story but the story isn’t baseless either, I know Mag has made the argument in the past as well but more centered around claiming Auric.