I think they’re not necessarily talking about open world but the freedom of choice. They mentioned that before, you had to have certain equipment to complete certain challenges. They want you to be able to think a little more outside the box like in Breath of the Wild in which we’ve seen many players come up with new ways in solving problems and discovering new things in this particular world of Hyrule. With the reception the game got, the sales it garnered, and the awards it’s earning from multiple media outlets, it’s hard to argue that this isn’t a formula to look into more for future games. They can eventually tweak things here and there to enhance the experience too.
He's already confirmed before the open world approach is now the new template for the series.