MK Tour is coming in 2019. Maybe if that becomes popular like Pokemon Go, then perhaps they make an MK game.
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.
Switch Friend Code: SW - 1286-0025-9138