Usually, with every big box expansion (such as TTK and Rise of Iron), there is also a full game bundle that gets released that includes the base game and all expansions up to that point. Both "Destiny - The Taken King - Legendary Edition" and "Destiny: The Collection" are examples of this. No such big box bundle has been announced for The Forsaken yet, but that doesn't mean one won't be available. You may have to wait until closer to release date to find out if there will be such. If one isn't announced though and you want the preorder bonuses, you'll need to preorder what is available to preorder, instead of holding out hope for something not announced.