At their current state, I don't see why Vault of Glass or Crota should be relevant anymore. The raid itself is fun (Crota... Meh), and the bosses have cool mechanics. The problem, is the weapons they give out. They're outdated and unusable in TTK, besides the normal crucible. However, if Bungie does decide to update the old raids with more/new content, than of course. I think the old raids should have a new difficulty option (TTK mode, or something). I mean, the VoG and Crota gear and weapons will have a year 2 drop; while the other difficulties will stay the same year 1. They could also replace enemies with their Taken counterparts, or add some Taken that aren't there to begin with (Cabal for example).