I chose galaxy because it was a huge Mario game on a platform with well over 50 million units under its belt at the time. And there's no way Splatoon is as highly regarded as a selling power house than Mario's 3D outings or even his 2D ones. If Mario 3D World was released on Switch with upgrades, I'd expect it to sell less. It's too similar to the previous game which to me at least, means lost interest for the sequel. I'd love to be wrong and I probably will be but this is what I think. Calling something a sequel and it looks like a 1:1 ratio with added content and same engine...that really doesn't rub me the right way. That would mean MK8 deluxe qualifies as a sequel which isn't true. This could go either way, there's no way to gauge if Splatoon will continue its momentum as a series. That's my prediction, don't throw stones at me just yet.
Unlike Galaxy 2, Splatoon 2 is launching on a new platform that's far more successful than the one its predecessor was tethered to. Splatoon 1 was held back by being on unpopular hardware, Splatoon 2 won't be.
Bet with Liquidlaser: I say PS5 and Xbox Series will sell more than 56 million combined by the end of 2023.