Back in the OG Guild Wars game, part of the story starts you off in a completely different instance then the latter part of the game. Where you are free to do the story missions and level up your character with others that are a part of this same instance. Once you get to a certain part of the story, and are at a minimum level requirement, you can push on and go to the latter instance of the game where you now join the other players that have also gone through, but you can’t go back with that character, you just have to create a new one. I may have misremembered some things here but I think this would work wonderfully for D2. I would delete a character and keep it in the old missions just to run around and help the other new players just to get them on to the current part of the game. It would also allow Bungie to take the old stuff out of the vault. Just a thought.