@Slimebeast
I'm sorry to disappoint, but I just cannot see it happening. I'm betting pretty big on this fact too, since I'm shorting a lot of shares of 360 stock over at SimExchange. Over 3 years, with the year starting the day that the 360 launched in NA, and assuming it gets to about 24 million by that point this year (it won't get a holiday boost yet), that would mean it has only averaged 7 million a year, even with one of the best lineups last holiday season. Yet you seem to believe it will increase yearly sales by about 2.5 million this year, even without the big hitters like Halo 3, Mass Effect, Bioshock, I could go on. You even said "The X360 has the BEST game support" which is an opinion in any case, yet it can't even manage sales similar to the PS2 in it's waning years (since the PS2 sold more in 2007 than the 360 did).
Now, every console for which we have solid yearly data, sales normally peak during the 3rd year (which the 360 is currently in), then start to decline. There are, however, slight differences in how the 3 markets work with this trend. My findings show Japan starts to decline first, but are quicker to adopt a console (hence why the PS3 will never win there, it was too late after the first year, but even the Wii's peak year is probably already behind it). The America's market starts at a good pace, increases up to the third year, then declines after that. Others has normally been slower to start the adoption process, but makes up for it in "legs," with the 5th year of the PS2 in Others being its best year, then dropping quickly. Here's a very quick picture to kind of illustrate this (you don't have to view it if you don't want to). It's just a rough drawing, and doesn't represent sales trends 100%, but you'll get the idea (I hope).
Now we can argue about price, games, whether the Wii is competing with the PS360 or not, and a whole lot of other fun stuff, but I'd rather not (least we bring Crazzy into this). So basically, this is where I stand:
As for price, the 360 price will always be greater than, or equal to, the Wii's price. And since the equal price part isn't helping the 360 in Europe (where equal price actually equals 50% sales). Dropping the price isn't the "fix all" that people seem to think it is. The GameCube, despite being cheaper at launch, and cheaper (and more powerful to boot) than the PS2, never "took off." Since I believe that the Wii directly competing with the 360 (and PS3 of course), and since the Wii will probably always be cheaper than the 360 (though I have been wrong about things before), the Wii will most likely always steal the majority of the users waiting for The Price is Right (and you're the next contestant!). So basically, price cuts aren't going to help that much, especially since the downward sales curve is too great to stop with a simply price cut.
As for games, the 360's line really is incredible. Though it hasn't helped sales all that much, compared to the PS3's relatively weak (but getting better) line-up, while the PS3 is more expensive (again showing price isn't everything). Also, the "really weak" line-up (according to the GameRankings and most "experts") hasn't hurt the Wii very much (see April NPD).
So all-in-all, even with price drops, and the great games that the 360 already has (and with more to come), it's unlikely that the 360 will hit much higher than 9 million in 2008, and then over the next 4 years (which would mean a lifespan of 7 years), to hit another 20 million, would have to average 5 million a year (which is about what I'd expect it to do). 7 million in 2009, 5 million in 2010, and then 2 million in 2011 and 2012, which is about 16 million, plus 24 million, equals 40 million.
Even assuming a little more generous sales decline (though that decline was more generous than the Xbox and GC decline, which is what they were based off of), one could assume 8 million in 2009, 6 million 2010, 5 million 2011, and then 3 million in 2012 (release of X720 lowers sales a bit more), or about 43 million (which I guess is more than my "40 million max" but still).
Either way, 50 million would be really pushing it (and I definitely see it as the ultimate max), and since SimExchange currently has lifetime sales of the 360 sitting at 57 million, I'll continue to short it because I just don't see that happening (nor do I see the 67 million for the PS3 that the SimExchange is currently predicting happening either). Sales just don't jump massively due to price cuts and games.