It's kinda futile trying to guess what kind of disruptive product Nintendo may or may not announce next year.. Perhaps looking at their patterns you may see their train of thought..
Wii Remote = Engaging, Exciting
Balance Board = Fitness, Exercise
Vitality Sensor = Calmness, Relaxation
New Peripheral = Motivational?
Who knows.. lol all we know is that these new propositions are designed to be disruptive agents. They aren't aimed at core users but new users that haven't bought the console yet or as Iwata put it, they create more people that change their perception from 'I am not interested in Wii' to 'I might be interested in Wii'.
Of course they will gradually create value for the core user (Shawn White for Balance Board, Eternal Darkness PLEASE for Vitality Sensor)
Basically what I'm saying is it'll use off the shelf parts, be relatively cheap, and it will not be directed at current Wii owners at first.