UPDATE: This info was claimed fake, but we will hopefully know official word about Mario Kart on Switch next week.
We are getting extremely close to the Nintendo Switch presentation which means some stores like GAME, Gamestop, and EB Games are getting some of their promotional stuff early so they can start all of that right after we hear the release date, price, and the launch titles. Well early in the morning on January 2nd, 2017 EB Games accidentally leaked something for Mario Kart 8 on the Nintendo Switch. They also listed the console, pro controller, Zelda, and Skyrim, but they were at a placeholder price at $119.
On the game case of the Maro Kart 8 Switch there is a little promotional part where it says the game will include a new Battle Mode, 24 Extra Tracks, and 10 New Characters. That is a big update from the Wii U version that was launched a couple years back now and this is better than just releasing a 9th one.
This gives us an idea what Nintendo will do with other games like Splatoon and Super Smash Bros. We can probably expect new weapons, maps, etc in Splatoon while in Smash we could probably expect new amiibo and new characters for the series.