It seems as if the Vault of Glass might be holding more secrets than what we have found.
Bungie revealed this during a live twitch stream, where Rob Adams (Lead World Artist), Gavin Irby (Senior Raid Designer), and Eric Osborne joined a stream clan called 'Dad of Destiny' where they were drilled questions, about the game. One of the questions was, Are there any more Chests in the Valut of Glass. Where it was followed up with a, "Yes, The answer is yes."
You can watch the whole interview here just skip to 52:25 to see the question.