Ohh boy here in offtopic you'll get the cold hard truth. Bungie develops the game like a content island mess and it' such a spaghetti from 3 different studios that actually expanding the engine would be a bit too much work for their standard. The best choice would just making Destiny 3 in house with their rules, compressed textures and all so they could actually expand on their "ever evolving universe" instead of copy-pasting the past and selling same -blam!- different day that they'll take away for "the living story" my -blam!-.