Going back to a 20 would NOT allow you to do nightfalls, weeklies, raids, or PoE. All things that are already avalible to people who BEAT THE GAME. I have 3 34's and have had the game sense beta. There is no logical sense it taking all those things away from people who have done everything BUT the new dlc. With that said, Whatever level you are currently at is the level you play as when the dlc drops. Only people who have to grind are new players.