It is hard to say at this point.
Zelda: BoTW has a magic that could revolutionize game development in a similar fashion as Mario 64, Zelda Link to the Past, Goldeneye, or OoT did, but none of those games reached the same level as did Wii Sports, Mario Kart Wii, or New Super Mario Bros. That is because they are epic game experiences that do not appeal to every consumer, however, in this case, BoTW is the system driver and might represent the standard for Switch games. Every Switch owner this year might very well buy a copy of Zelda. If Switch sells through 14 million or so, then we could easily see Zelda top 10 million on that merit alone, but it is too early to tell.
The energy that Zelda has at the moment could transition into Mario Kart 8 sales going into the holiday due to a different audience.
