No, I am not gonna fall for this.
I think some RPG elements are necessary this time. Open world games are huge in scale, so they probably need to have content to keep players engaged. This is why many people complain that many open world games are empty because the game is not engaging enough. It cannot be achieved only by either exploration or gameplay systems. Open world games usually need both to keep players engaged. IMO, many open world games failed to achieve this and thus, many games are either called bloated (the world is huge, but too little stuff to do) or became "checklist simulator" (like many Ubisoft's games). In order to succeed in creating a good open world game, apart from building a good world map, Nintendo really need to consider about adding some RPG elements to the game as I don't feel that collecting heart pieces can keep players engaged enough.
Apart from these two elements, a sense of progression is very important, especially in open world games. In many genres, it is important that the players could feel that their avatar is continuing to grow. For open world games, this idea also extended to traversal of the world. If the players are always driving the same car in the same world, they will feel bored easily. So players need to be given opportunity to upgrade their means of traversal. For example, in Xenoblade Chronicles X, you can get the Skell around Chapter 6, and the Skell can fly in Chapter 9. This approach freshens up the means of exploration and creates a very important sense of progression. That is why I argue that Epona may receive mechanical parts to upgrade the horseshoes so that it can travel to places you cannot reach before, like walking on the surface of water.
Overall, I am quite optimistic towards the game. Nintendo is a master of creating great games, and I expect it to produce a good open world game, or even shaken up the genre and create a new experience for us.