I just wanted to post this, in case it might work. I know I'm telling you how to write your game from my comfy chair, and I expect everything is more complex than I realise, but just in case this is feasible, and nobody at Bungie has already thought of it, here goes. You have these awesome PvP maps already. Each one suggests story missions as they stand. Your PvE players, though, never get to see them. You also have removed the Queen's Bounties in part because of complaints over it all being repetitive, running the same missions again. So, why not throw some level designers at the PvP maps, and set some small and quick but entirely new challenges? Re-use your named bad-guys, and keep it simple. It will give the players who don't like PvP about 30% again more world to explore, and will only take level design work, rather than the vast effort of building a new area. Use a similar bounty-system to "earn" the right to start the missions, and you have a whole bundle of new content for minimal effort. They don't have to be all the same level of challenge, and you don't have to come up with a way in which they should be completed - let the ingenuity of the cheese-finders from the Raids loose on something you don't have to police so heavily.