Splatoon, like Mario Kart, is a game casual players can get into. Zelda, not so much. So yes, I totally agree that it can over take it commercially. It will depend on how great Nintendo is at evolving the IP though. Mario Kart didn't get to where it got by them rehashing the series. They made great strides in the gameplay to get to where it is now. Splatoon will need to do the same thing.
Sadly, what that "thing" is will probably be lessening the difficulty curve.







