Lets face it,unless it will be a big hit on a Stranger Things or House of Cards level,no way this show will last more than 3 seasons! Netflix usually cancels all their shows after season 3. The exceptions gets made if they really find a big big hit,but i doubt One Piece will have that level of success,its a tv show based on a manga after all,so its not a show for everybody,so i think this show wont tell the complete story and around mid-season 2 will change completely from the manga to develop its own ending. Or it wont have a ending at all!