Don't forget that the game isn't out in Europe until tommorow, I'm sure that this game will apeal to a lot of European Wii owners (especially since we got a censured version of No More Heroes - so this is the first of it's "kind" over here) - so that should also boost it's sales significantly..
I'm quite sure, that this game will see good stable sales for quite a while, and it most likely will pass a milion within the fall - since the Wii's demographic's often tend to indicate, that a lot of Wii owners don't buy games as instantly as on the other consoles, but still buy many of the more high profiled games eventually..
So I think, that it's a bit early and unsafe to say that it has been confirmed that Mad World is not selling..