Updated through 12/31/21 thanks to Nintendo's recent sales update!
Switch now has 13 games exceeding 10 million (though Wii's 10 million sellers have still sold more combined due to Wii Sports, but that will change soon).
Some notable achievements: SWSH have surpassed GS and MK8DX has surpassed Super Mario Bros. and ACNH has surpassed MKWii. BDSP just joined and is already super close to LGPE (which is close to passing both ORAS and Yellow). I wouldn't be surprised if BDSP passes both of them before LGPE does. NSMBU DX is tied with HGSS.
Which games do you guys think will hit 10m in the next quarter and what else do you think will hit 10m this year? I think Legends will easily do it and probably reach 12-13m by the end of March. Other than that, I think it's a little too soon for Mario Maker 2 and Bowser's Fury to reach it, but I do expect them to hit 10m this year. I could see Splatoon 3 reaching 10m potentially this year. BOTW2 is an easy 10m this year as well. Monster Hunter Rise should also hit 10m, but this is a thread for first party games only.