We'll see. The fact that Wii at the time was still a heavy seller and didn't manage to garner more sales is more telling I think. But if we're talking sequel territory, let's jump from Galaxy 2 to 3D World... you can't really guarantee anything at this point in time. We don't know how the fanbase is going to react to another Splatoon. There's always the vocal minority to kinda bolster and rally the troops but week 1 for me will be the most telling. However, in retrospect 3 million might have been a bit too low, I understand that much. I'll say 4.5 LT. It really depends on how Switch sells and if Splatoon 1 players see enough incentive to buy the second one. For me, I don't as I see a game running off the exact same engine with a few new perks here and there. And that's just me, I'm sure there are fans who think that's enough to come back for more. Again, I'd love to be wrong, I hope I'm wrong but at this point I just don't see the appeal for Splatoon 2. Japan disagrees whole heartedly of course but yeah, that's where I stand.
Galaxy to 3D World isn't really a good comparison as that's going from a successful console to an unsuccessful one, the opposite of Splatoon.
Splatoon will be more analogous to Smash Bros, which grew from 5-7 million on N64 and Gamecube to 13 million on Wii.
Mkay, how do you fancy Metroid Prime? And even then that's a cheap shot because that's the only dead and gone era we have of an uncessessful Nintendo platform that we can compare to a successor (Wii). Can't really compare Switch to Wii U LT right now so its even harder to gauge. There simply isn't enough data to make an educated guess. My point is, we'll never know when and to what extent fans will get turned off by a franchise. I think the Splatoon fanbase will respond well to this game but not as well as everyone is expecting it to.