The original Xenoblade only reached the 1m sold when we take into account all the versions (OG Wii, VC Wii on WiiU and N3DS), and that was after years of people and media praising this game. X would have reached the 1m units sold if the WiiU had a bigger userbase, but as it is, is a niche game on a niche console.
I hope the game becomes avalible on the NX, considering how expensive and time consuming its developement cycle must have been, I'm sure they will push it there too.
Also, this gave me flashbacks of my Splatoon VS Xenoblade X thread. XD