It could but probably won't. It looks like an excellent game, it's a fresh IP, it's a shooter and people really liked it post-e3. Splatoon could have appeal to those wanting a new experience, to those who like shooters, and especially to kids and parents who like the characters and non-violent approach to a shooter.
But it would need a significant marketing push to get the word out, and people really aren't fond of the Wii U, so it's not likely that it will have a major impact.
I do think Wii U will have a solid year though, with this and other titles plus a price cut making this most likely the system's best year to date.








