I voted 15 - 17m. The game has serious legs. I defintely think it will cross the 15m mark. If I voted wrong, then it's because my guess was too low.
I don't think we are getting a truely new 2D Mario game on the Switch. Instead we are getting stuff like Mario Maker 2 and Super Mario 35. These are variations on the 2D Mario theme, but I don't think we are getting a full new entry in the traditional sense.