I don't think there's much new info on what's in the DLC but I found this bit right at the end:
Finally, the interviewer asks Miyazaki if he would like to make another Elden Ring-sized game, and the answer is a yes. While he is not sure if they will be able to immediately start work on such a game, he would like to. He believes that he is not alone in the development team in wanting to put the experience of working on Elden Ring towards a new game, and more than anything, making a huge world and adventure is fun and exciting to him.