Well, a little breakdown.
Wii Play is linked to the Wii's sales. Wii is down 25% YoY, Wii Play is down 33%. Essentially, Wii Play will keep selling 25-33% of the Wii's sales till the end of the gen. That's the most likely scenario.
As a result, we get the question:
How much will the Wii sell? Wii Play is likely to sell 25-33% of the Wii.
The Wii is now at 53M, and Wii Play at 24M.
If the Wii ends at 100M, that will be 36M-39M
If the Wii ends at 120M, that will be 40M-45M
If the Wii ends at 140M, that will be 45M-53M
If the Wii ends at 160M, that will be 51M-59M
Now, how much is Wii Fit likely to sell?
It's currently at 21M.
Edit: The rest of my post... dissapeared?