I don't think Nintendo needs reassurance of the franchise's success on giving a call for a new game. If all, an full priced MK port selling 10 million units in 1 year and a half should be more than enough.
I do think they will make a new MK for Switch eventually, but not now. Maybe 2020 or 2021.
Yeah I get what you mean. Perhaps we will see signs of a new MK game once the port is selling at a slower rate.
Pocky Lover Boy!