2001 GameCube Animal Crossing 2.32 million[1]
2005 NDS Animal Crossing: Wild World 11.75 million[1](March 2015)
2008 Wii Animal Crossing: City Folk 4.32 million [1](December 2013)
2013 3DS Animal Crossing: New Leaf 11.78 million [3] (June 2018)

 

Animal Crossing is much more popular on handheld devices, on 3DS we had huge increase popularity of IP, its sold same number like it sold on DS despite much smaller install base, on Switch we will probably have more incrase of popularity of IP, and on Switch generally and specially Nintendo games are selling very good and much better than they did on past Nintendo platforms (including 3DS).

With all that on mind I think that Animal Crossing will have problem passing 15m+.