I'm saying 50m. Even that will be a challenge - going from 17m (in a fiscal year) to 30m - is anything but trivial (that comes to 2.5m/month).
Predicting Ninty will forecast 25m for next fiscal year - leaving a little room to up it a couple of times over.
Quick predictions (March '09)
Wii: 50m
360: 25m
PS3: 20m
Gesta Non Verba
Nocturnal is helping companies get cheaper game ratings in Australia:
Wii code: 2263 4706 2910 1099