Not a chance. They said they will release Natal in Fall 2010 and It's considered a re-launch of the 360 console with some tweaks (I've heard rumors of upgrading the 360, but I'm guessing either a re-design or just a larger hard drive along with the Natal add on). If anything Natal will be given some time depending on sales.

If Natal is a huge success and places the 360 back to second place every week I think we will see MS keeping the 360 till atleast 2012. If it fails then theres a chance we might see a NextBox as early as 2011.

Bottom line is with the high costs of next generation game development, and the rising profit from Nintendo and now Microsoft's side we will see next generation consoles lasting longer and longer which works for me.

Relaunch of the 360 with Natal in 2010

Nextbox in 2012 at the earliest

they may reuse hardware, add more ram and bunlde it with natal at 299
it play old games, but some games will be new console only.

I say 2012 the earliest.

If by "NextBox" you mean NATAL + redesigned/slimmer 360 bundled together for $250 in 2010 ... then yes.

I think actually NATAL (whatever they end up naming it) is going to become a brand in itself and MS will just slap a "using XBox 360 technology" sticker on the box under the Natal marquee. Kinda like the "Intel Inside" thing on PCs. 

Natal 2010; Nextbox rumors 2011; Nextbox arrival 2012-13; no ditching the 360 upon launch either.

no

As others have said, I think the next xbox won't be out before 2012. One reason is that already many of their customers feels burnt because of the hardware troubles with xbox360, so they will not risk alienating those people further by rushing in to a new generation. The xbox lifespan was way too short, the 360's lifespan looks to be much better.