Correct me if I'm wrong on the lore, isn't the Vault of Glass the only content in the game that literally exists outside of the timeline?
Like, Crota's End has a specific place in the storyline, and is 'completable' since it builds to the Taken King but Vault of Glass technically happens outside of time, but killing Atheon has no effect on the story (so far) since the battle actually takes place before Destiny and after Destiny and during Destiny's storyline?
This is a good question I don't think anyone can answer for sure. VoG isn't completely outside the timeline though, people know and talk about it.
-The Archive mission has Ghost dialogue at the end which references the Vault of Glass. Some information is stored there about VoG, presumably from Dr. Shinn's work. The Cryptarchs learn about it and study it.
-Kabr got out and talked about it. Some of his Grimoire quotes are second-hand from a Hunter named Pahanin who Kabr talked to about VoG after having been there. His fire team being erased by the Gorgons lead to Pahanin developing the Super Good Advice weapon.
-GI article implies that you are recognized in game as the Guardian who conquered VoG and defeated Crota which explains why you are chosen to confront Oryx.
Ultimately I don't think it's outside the timeline, but a unique part of space/time that operates under Vex rules of reality.
Gorgon Grimoire said:
Deep in the Vault of Glass, the fabric of reality bends to the will of the Vex.
The Gorgons are said to only have their ontological power inside VoG. They can decide what is real or not real, but only for things/people that enter VoG. They can't erase the speaker or the Traveller from existence. A major part of the Vex mission is to write themselves into the fabric of all reality, so that they could wield this power everywhere.
Drizz - why not raid-specific bounties? )
This would be sweet, especially if they tied it into the Quest line style of bounties they are talking about for TTK. There isn't a VoG or Vex related vendor/quest-giver right now so who knows how they'd do it but it's definitely a smart option.