WM was the answer to Move and Natal and besides that, I think Nintendo is going to use the Vitality Sensor to provide a new distinction between Wii and it's competitors. It's all about providing something different, new and unique with Nintendo and the Wii Vitality Sensor will allow Nintendo to craft a gaming experience that is completely unique.
differentiation may be the reason behind Iwata saying that Wii Party use the Wii Remote's unique capabilities to it's fullest (the hide and seek game for example, which the Move and obviously Natal cannot do). So it's no all about the motion controls, but the unique device that the Wii Remote is.
That again, is differentiation, and Nintendo will continue to try to position the Wii as 'different'.
