The real test will be who's still using it in a few months after the hubub has died down.
I bought one for myself (a core gamer) and one for my sister's household (enjoys gaming, but does not play many titles).
I've already given them the pitch as well as the brief about the upcoming hype.
They don't have to do a thing in terms of ordering it, I'm going to set it up and leave it for them to play with. It's a health conscious house, both in terms of exercise and diet, so none of the fitness principles and concepts are new to them. They both go to the gym, and they regularly buy sports/fitness equipment.
Will it be entertaining or useful? If it's the former, I expect it will not be used after a few months (which will be confirmed as soon as the board disappears into storage somewhere). If it's the latter, I would imagine my sister might actually start using it on a regular basis if she doesn't find it to be too elementary.
For myself, if it's entertaining, I expect to still be using mine, probably through 2008, even if I'm just using it as a monitor (along with a body fat/water % measuring scale), rather than for exercise. If it's fantastic (fun and actually shows results beyond changes in Wii statistics) I could see this as the primary reason for using the Wii until some 3rd party releases suited to my tastes are available.
For the record, I do not go to the gym; I lift free weights at home, body weight exercises (push ups, crunches/sit ups, pull ups) and run (no tracks, no treadmills). I watch what I eat. 8 years of Army PT, over 20 years of various martial arts. So yes, I like to exercise.
