Mario Kart is a force to be reckoned with. I tried the Game comparison tool on this website and compared Deluxe with MK7 and MKDS and guess what... The game is even outpacing the DS iteration. So it might end up at 30 million, becoming the 2nd best selling Mario Kart of all time!
Here are official shipments for recent Mario Kart titles after 6 quarters
Mario Kart DS-7.03 million
Mario Kart Wii-18.36 million
Mario Kart 7-8.08 million
Mario Kart 8-5.87 million
Mario Kart 8 Deluxe-11.71 million
When the herd loses its way, the shepard must kill the bull that leads them astray.