Thing is - part of classic elf archetype, as I (and many other people) understand it, is to stay allied with Humans and Dwarves. And as much as I love Blood Elves - I rather could not say, they deal with that part well
Best solution in my opinion, is to differentiate from existing High Elves those, who will not be willing to follow Alleria's path to the end, as they were not willing to suck magic from living creatures before, and give them story about finding new ways, slightly turned in favor of nature, reusing some WC2 concepts (to address nostalgia), use some proposed here bronze skins - as consequence of either new lifestyle, crossbreeding, or their own balance searchings in other way. Use Silver Covenant just in recruiting scenario.
That story would in fact strongly follow path of Tolkien elves - who after destruction of Beleriand, become forced to search new settlements, hidden in forests, mountains or underground, between their less noble relatives. And such - it is classic to the core.
What does in fact stop us, from supposition, that there might be exist some unknown refuge camps in all that empty mountains of Eastern Kingdoms, during reigns of Scourge and Horde, now rediscovered after Alliances offensive?