Personally, as the most efficient approach to reduce dev time, all of the Zombies maps, especially from Black Ops Cold War Zombies for the Dark Aether maps could be revitalized with BO7 mechanics and new features (Ex: omnimovement, eternal perks, more than 13 total perks and gobblegums), while BO6 maps can be simply carried over. This could make BO7 the next Black Ops 3 when it comes to being a "one game package" for the Dark Aether Saga.