What makes no sense is leaving tons of money on the table that would also please a majority of the fanbase. I don't think Nintendo is going to ignore the fact that far more fans like Mario Kart than any other racer just cause a port already exist on the system. A 20+ million seller like MK9, even if it were to cut MK8D's legs to 0 (lol no), would still net a lot more profit than the 2-3 million sales Diddy Kong/F-Zero/Kirby Air Ride would generate. From both a consumer and business standpoint, MK9 should hold more priority than most other games let alone just racers.
I've read a rumor that Nintendo is strongly considering to delay Breath of the Wild 2 until 2025 because the first game is still selling so well.
I've also read another rumor that stated that Animal Crossing and the remake of Xenoblade Chronicles are the last first party releases in 2020 because there's no reason to release any more new games when so many of the old ones are still doing so well.
Wow people. Zelda had new story, making it a new experience. As does Xenoblade. Mario kart 9 won't really offer much more than 8, some new tracks and maybe some new characters mixed with a lot of re used tracks from older games, and it won't even look better being on the same system.
If they said all new tracks, tons of new characters, tons of new modes, redid the online to make it a proper esport, and added a story mode then that would be fine, but they won't do all that. Just adding new tracks is DLC to me, and a lot won't buy it already having 8 which will look just as good.
They should wait until the next device so they can make a huge graphical leap forward with time to build tons of new features, 60fps, new online modes and give the Switch 2 the proper launch game it needs so that it won't repeat the success/failure cycle Nintendo has from one gen to the next. The long game is the only thing that matters.
I shouldn't even have to explain why a sequel to Zelda and XC would bring a lot more new elements than a sequel to a non-story mode kart racer.