Let's take a look at the sales for last year's timeframe going from September to year's end.

http://vgchartz.com/hwcomps.php?cons1=Wii®1=All&cons2=PS3®2=All&cons3=X360®3=All&start=39327&end=39446

Looking at the table and the graphs, we can notice how big are sales during the last third of the year.

^ Those are 2007 total sales for each console, and as we can see sales during this time of the year represent more than half of the total sales.

In 2007 from September to year's end: Wii sold 50.14% of its total 2007 sales, PS3 sold 57.15% of the total sales and 360 sold 60.96% of the total.

Durign this year so far, this are the total sales until August end.

If trends were to continue using last year's numbers we could expect something like this:

Wii at 25,234,528 units for the entire year, placing it at a total of 44,430,328 units.

PS3 at 14,840,534 units for the entire year, placing it at a total of 23,699,760 units.

X360 at 11,985,404 units for the entire year, placing it at a total of 27,831,894 units.

But there are things going on that will prevent this from happening. First PS3 saw a price cut last year at this time of the year, that allowed it to boost its sales a lot, while this year only a new model for the same price will be available. So we can expect sales not to follow this same pattern, considering that its biggest games of the year have already been released, so a boost from them is unlikely.

Second, 360 had Halo 3 at this time of the year last year, and this year there's nothing comparable to that. The only thing that may have an effect is the upcoming price cut, but we can expect sales to be lower than last year because there's no Halo this year. YoY sales for the last weeks have been lower than last years same weeks, that should be taken into account too.

Lastly, Wii is up from last year during this same timeframe. Selling at a constant 300 - 350k weekly average, that's higher than a lot of weeks from last year at this same times, where Wii was selling in the low 200k's. With this year's increased manufacturing capabilities Wii sales should remain up. So we can expect a big holiday if supply holds up to demand.

Taking all this into account I think a safe bet for the Wii will be 45 million, 21.5 million for the PS3 and 26 million for the 360.