I agree Nintendo make shit tons of money from this cash grabs 2D Marios, that's why they are still making it
However, Mario Kart 8 deluxe sold three times more than the original game for Wii U, meaning public stills THIRSTY for a Mario Kart, no matter if it's a port or not. It's clear that while there is still a huge market for 2D Mario, this market is just not as big as it used to be.
I think a brand new 2D Mario game will sell better than a U Deluxe, and yes more than Mario Maker too, but I don't see 2D Mario been as dominant as in the past when they easily outsold their 3D counterparts, so I see 2D Mario's relevance slowly disappearing with time and becoming a more niche game, while the A-list Mario games from now will be wither 3D Marios or other Mario's series (like Mario Kart)