Over at GamesIndustry.biz, Dr. Serkan Toto at Kantan Games leaks supposed insider knowledge regarding the next Mario Kart:

Quote"I am aware Mario Kart 8 Deluxe is still selling very well on the Nintendo Switch, but Mario Kart 9 is in active development (and comes with a new twist) and Nintendo could tease it this year."

https://www.gamesindustry.biz/articles/2022-01-05-what-happens-to-gaming-in-2022-analysts-offer-their-predictions