Honestly, with how expertly music is being handled with Mario, in thanks from the stuff done with Grant Kirkhope, Koji Kondo, and the various teams responsible for Mario Odyssey and Mario Kart 8 Deluxe; I do think they're going to have a lot to say in regards to music representation on music with Nintendo. Because in a way, it really does connect a lot of the experience of playing the game.
As far as what I'm thinking..I do think there will be a heavy reliance on MK8's tracks, more specifically Bowser's Castle, Rainbow Road, and the Mario Kart Stadium theme's as central themes for when needed.