Hey Riot! Regarding limited/legacy edition skins...

When will the vault open again? I figure this question must be asked a lot, but I thought I would try again considering the impending Prehistoric skins. It would be cool if there was a Blast-to-the-Past sale coinciding with their release that offered a few legacy skins! I know that I've had my eye fixed on Void Nocturne for a while, but alas...