wii fit will be big, since there are people everywhere who want to lose weight but do not want to go to gyms (because they are ashamed of their current condition) or just want to have some usefull tool to stay in shape. if wiifit can 'help' at least a bit in both the cases it will be big with legs like a giant.
maybe hospitals will want to use wii fit for getting back to shape (after playing wii sports to get back to basics) then it could be even bigger (maybe like 100 wii's xtra next to the wii fits. but it is still extra :D)







