Basically, i'd keep the High Elf skin, but remodel a whole different skeleton. So it'd be impossible to mistake the animations of a High Elf from the Blood Elf (unlike Void Elves who are a carbon copy of the Blood Elf skeleton), which would allow for a clear distinction, without the need of too drastic a resking. And even such a resking wouldn't bother me. High Elf already underwent one, from Vanilla to TBC, and the Zandalari got 3 and a half (Vanilla/Wrath;MoP + ToT and BfA) without necessitating any explanations. The fifteen years of a very different life of the High Elf could already be starting to show, especially if you join the Silver Covenant with the High vale elves.