If this is all true, then I guess Mario Kart 8 might've originally been due for an ideal newcomer after all, one that doesn't seem questionable and hasn't been playable in any other kind of Mario spinoff. One thing that's still to be figured out right now is if the additional characters of the Switch port were characters intended for the Wii U game that never made it due to time constraints, of which did not include Kamek up until the MK8BP came around. But the Kamek icon found in the game's data of the Wii U game could explain why he was chosen to be in the MK8BP (it was even seemingly teased through an advertisement in Coconut Mall).