There are a couple of factors to also consider in this.
SSBB is coming out before then, Mario Kart will be out about that time, Wii Fit launches before then as well. All of these should move systems, unless we really start to see a drop off from what we saw last year this time in the US I think it's perfectly reasonable to think that the Wii will catch up to the 360 by the end of June.
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I don't recall them saying that, got a link?
There are a couple of factors to also consider in this.
SSBB is coming out before then, Mario Kart will be out about that time, Wii Fit launches before then as well. All of these should move systems, unless we really start to see a drop off from what we saw last year this time in the US I think it's perfectly reasonable to think that the Wii will catch up to the 360 by the end of June.