If SwSh has the same legs of XY it will lead to a maximum of 4-5 million in sales, not 10
And keep in mind, XY was the leggiest Pokemon since at least GS, but I do believe the DLC plus lack of a third version will do wonders for SwSh, making 23-24 million the goal for this one. Game Freak is probably releasing another main entry in 2022, so this game maybe won't experience enough time to outsell GS, I'm thinking there is a 50% chance of outselling it