the 360 will not reach 50 million. i say somewhere around 28 -34 million LTD

i think that microsoft will pull the plug with the 360 as it did with the original xbox, and that is why it will not sell more than 50 millions

 Sounds reasonable enough to me.

I don't think so, I think with the release of the final three well sold XBox sequels, Star Wars, GTA and Fable the install base should be at least on par with the original XBox this christmas. But then I expect the platform to fade away slowly, due to more fierce competition with the PS3.

How much the 360 will sell in the end depends upon how long Microsoft is going to support this platform, my guess would be 30 to 35 million. Europe and Japan are IMO as good as a lost fight for the long run, for the US I expect market saturation to hit the platform when the platform goes beyond the original XBox install base.

I should made this thread will the XBox 360 reach 40 million LTD?

The only way the 360 could top out at such a low number would be if MS stops selling it at the end of 2008 and brings out a new console. Below are actual sales trends for the 360:

2006 sales: 6.7 m

2007 sales: 8.0 m

1st quarter 2006 sales: 1.1 m

1st quarter 2007 sales: 1.2 m

1st quarter 2008 sales: 1.7 m

During the first quarter of 2008, the 360 is selling 55% ahead of 1st quarter 2006, and 42% ahead of 1st quarter 2007. Assuming this trend continues and the 360 sells 55% more in 2008 than 2007, then that will be 12.4 m sold in 2008, which will put the 360 at a grand total of 28.5 m by the end of this year.

Even if the 360 were to inexplicably drop in sales and only track 2007's numbers, 8 m, that would still put the grand total of 360s at 24.1 m by the end of 2008, almost at the bottom of your "lifetime" sales range. The only way I could see the 360 not reaching past 30 m lifetime sales would be if MS decided to stop selling it by the end of this year. Considering they're actually making a profit from the system now, and still have yet to see sales from the $199 price point, I can't imagine them getting out the race that early.

Do you know something you could share with the rest of us regarding MS' future console plans?

EDIT: changed some of the numbers above to reflect real math instead of the imagination math I was using  

why not ?
PS3 was dead in the middle of last year and it return at the end of it
X360 can return especialy after the price cut in NA

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I expect 40-45 m at the end

It could reach 50 million, but I see it selling 40-45 million.

Take a look at my analysis above.  Unless MS pulls the console from the market before the end of 2009, I don't see how it *couldn't* reach at least 40 m. 

Here's my guesses for the end of this gen:

Xbox 360: 40- 45 million.
PS3: At least 70 million. I'd never rule out the possibility of it reaching 100 million.
Wii: God knows, I'm really not sure about the Wii. It'll beat the other 2 and probably come close to PS2 numbers.