It's hard to imagine that new content would be coming to Mario Kart 8 Deluxe, of all games. That's especially considering that already a fairly complete collection of everything that had already come to Nintendo Wii U. But Nintendo isn't quite finished with its kart racer just yet, as the publisher announced out of the blue that Link would get a special outfit that would tie to his latest adventure.
This update will add Link's Champion's Tunic and his Master Cycle Zero (yes, remember that Link has a motorcycle in Breath of the Wild) to allow him to ride in style. With Ancient Tires and Paraglider parts also in place, Link's full Breath of the Wild ensemble should be complete.
Mario Kart 8 Deluxe version 1.6 should be available for download right now.