Wii there be a Mario Kart 9 on the Switch?

It seems strange to even ask this question with how Mario Kart has been handled before the Switch era. However the team behind ARMS is mostly the team that has been working on Mario Kart for years and if the game blows up like Splatoon there are sure to be at least a few updates.  We also don't know if Mario Kart 8 Deluxe is Nintendo's 1 Mario Kart for the Switch or not and how do you top a Mario Kart with 42 characters, 48 tracks, 5 battle modes, online and the most items to date? If you ask me Nintendo should just keep making DLC for Mario Kart 8 where they keep building on the game and it also lets most of the team work on other new projects like ARMS. On the other hand I understand that Nintendo will likely want to come out with a true new Mario Kart sooner rather then late with it being there best selling game series.

Hm, I would think there still will be, maybe a bit farther in. The only reason is because unless they plan on releasing more DLC or something for 8, then there isn't enough to state Deluxe as its own thing for a series like this. Though at the same time I wouldn't be surprised to see them claim Deluxe as the Switch's Mario Kart. And I do agree with you that I would rather see them build up more for 8, especially since it already has so much brought over, but if they were able to top it, then I'd want to see how.

I think it depends on exactly what type of Mario Kart game. I can totally see there being a Mario Kart down the line that's more of a spin-off than a full new game, or a "new way" to play Mario Kart. It's also possible we could finally be seeing Super Smash Kart in a few years.

I do think right now the team's main focus is ARMS, like you said it could blow up like Splatoon.