Was there a timeframe given when this prediction was made? Otherwise 'Wii sales will eventually drop off' for whatever reason isn't exactly hard to predict.
A product with a finite shelf life will eventually stop selling after all, and you can make the same vague and unspecific prediction about anything with such a life cycle. So basically in order to be wrong the Wii would have needed to keep selling forever and never be replaced, which was totally likely...
We have a new Nostradamus here people.
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