I'm creating this thread to give an idea about what we might expect for December based on 2001 data for PS2 (when it was available for one year), and 2002 for GC & Xbox.  For the sake of comparison, I am including 360 with Wii & PS3 even though it had it's first full year last year.

In 2001..PS2's December sales were 8x greater than the weakest monthly sales.

In 2002...GC's December sales were 10x greater than the weakest monthly sales.

In 2002 Xbox's December sales were 13x greater than the weakest monthly sales.

Going by the weakest monthly sales for Wii, PS3, and 360 that would mean, with Wii using the PS2 rate, 360 using the Xbox rate, and PS3 using the GC rate, we would arrive at NPD December figures like this:

Wii - 2,072,000 (259k x 8)

360 - 2,015,000 (155k x 13)

PS3 - 820,000 (82k x 10)

With the year still young, it is possible that all three consoles could set new lows, but for now, I would expect those figures to be in the ballpark, even though the rate won't hold up exactly as it did last generation.

I had picked this separately.

console - NA (WW)
wii - 1.2m (3.2)
360 - 750k (1.6)
PS3 - 650k (2)

interesting topic.

So is that xbox number supposed to be 13 at the top? or is the 360 number supposed to be multiplied by 12 

Isn't 259k the weekly sales not the monthly sales or did you use weekly sales in your analysis. Just curious because you say PS2's December (Month) sales are 8x greater than the weakest (Month) sales but then use 259k which I thought the Wii did in a good week. Might of completly missed something though just noticed it at a glance.

259k is the Wii's sales for the weakest USA month.

Sorry just misread like I thought on my part missed the titles intial claim of U.S. month and assumed world.

fixed your error. ;) 360 less than 2m.

I would bet:
Wii - 1.700.000
X360 - 1.450.000
PS3 - 800.000

Actually, both extrapolations should have been x13, not by x12 revolutions, so that was the error..still good eye.

Why did you use the 8x from PS2 for Wii and the 10x from Gamecube for PS3?

Btw, were any of those consoles supply constrained in those lowest months? Cause that could give have a big influence on the factor you end up using.