Board Thread:General Discussion/@comment-62.255.98.169-20130504143516/@comment-78.60.64.99-20140206140835

In the wiki says: "It is also speculated that the toxin was merely a suppressant that degenerated the once-great race, and since surface-dwelling Falmer would no longer need to ingest the toxin, they might, over generations, re-evolve back into snow elves."

So they probably can.