Can Splatoon Sell/Ship 4mil+ Copies WW Lifetime? [UPDATE: 4.06mil By First Years End Only!)

[WhiteEaglePL]

Has the potential to do so. But it's up to Nintendo.
I think it currently it would be 3.1m max due to legs, though its likely a highly inaccurate guess as we don't know any numbers yet.

Although it looks like Japan will get 130K FW at least.