I could be wrong, but I have a feeling one of Nintendo's core strategies with the Wii is to keep interest in the system high (in the non-gamer crowd) through the introduction of unconventional add-ons. Now (generally speaking) this is a bad strategy because few people are willing to pick up a system and the add-on so the add-ons never sell well enough to be well supported by third parties. I expect Nintendo will get around this hurdle by creating better and better bundles which include these add-ons so that all systems sold from then on have that capability (meaning that if your system continues to sell well the add-on should be well supported).
This year the Wii bundle could become a Wii, Wiimote, Nunchuck, Balance Board, Wii Sports and Wii Fit for $250 (They could probably sell it for $200 if they wanted); next year they can (potentially) continue adding things on to the bundle as developers see value in supporting the current add-ons or they could move towards price-cuts.
Hypothetically speaking a Wii, 2 Wiimotes, 2 Nunchucks, a Balance Board, Wii Sports and Wii Fit for $200 is such a family friendly product at such a family friendly price that it can easily compete against a XBox 360 priemium or 60GB PS3 at the same price.
