I know this might sound like a terrible idea but think about it the open world is incredibly beautiful and well made to the point where i honestly dont mind if they reused it ofcourse they can make some changes and even add some regions but this will drastically reduce development time and give them more of a room to focus on the game design aspect and fleshing out the world more by having it being more interactive with better npcs, better gameplay mechanics, longer main story and more explorable buildings etc... i personally would much rather have a fully realized but reused open world than a new open world that is full of wasted potential.