I do think a split was created simply because a new market was created, or unearthed after having been gone a long time. So then all of a sudden there are two markets.
I think Nintendo first party titles have always been an excellent hybrid between the depth of hardcore and the breadth of casual/accessible gameplay. The problem is that they have always been showcased on a console that hardcore people abhor.
WiiU will inevitably lose a decent amount of the new expanded market that the wii created with it's accessible gameplay, but that is the price for making yourself attractive to a hardcore audience. They'll achieve the middle ground they want, just it probably won't strike as big as the Wii did.
But potentially having a middle ground platform for the first time is more of an achievement in the medium than sales numbers are







