Isn't it being fabbed by IBM/GloFo, who can't make jaguar cores?

Not according to VGLeaks, they always supported the 8x Jaguar spec - same as Orbis. We'll see in a few months.

Anyway, IMO an x86 architecture makes much more sense for MS, actually even more than for Sony.

I expect a cut-down version of Windows 8 running on Durango, and integration with the Windows store. It could be a big selling point for them if they had a common infrastructure for deployment, so that a developer can code an Application or smallish downloadable game under the constraints of a common set of APIs and make it available for Windows 8 PC and NextBox without the need for explicit tailoring for the CPU architecture.

Thus PowerPC architecture would be good for compatibility with the 360, but not looking forward to the curated closed ecosystem of desktop Windows... unless with IBM they are developing a smallish SoC for hardware assisted BC.

Yes, they do that to explain the difference between the 360 in order Power PC CPU and the new Jaguar in Durango to illustrate why despite 1.6 ghz a Jaguar core is stronger than a 3.2 Ghz Xenon core in the 360.

It's GDDR3 memory, and GDDR3 memory has less latency than GDDR5 memory.

I can have a 100Mbps uplink to the Internet, but if my latency is 500ms, a 10Mbps connection with 10ms latency will always be faster.  The higher latency of GDDR5 memory undoes the performance the higher bandwidth offers.  By using eSRAM with GDDR3 memory, Microsoft more than makes up for the lower bandwidth. 

Just to people not make confusion again.

- Nextbox uses DDR3 @ 68GB/s (plus eSRAM @ 102GB/s)
- PS3 uses GDDR5 @ 172GB/s

Its not that simple. If the rumors were true at one point. MS designed an Apu and included 32 MB Esram in it. Thats a huge chunk of silicon. But it was the only way MS was able to include 8gb DDR3 because without the Esram the GPU would not get data fast enough to max it out. MS planned early for the 8gb basically the whole system is build around it. Back then 8gb GDDR5 was not even an option. Sony planned with 2-4gb and lucked out that just recentlx the chip density of GDDR5 increased.Durangos Gpu was slimmed down so the 32 MB Esram would fit on the chip. 

Sony just lucked out they had no Esram so they were able to put all of the additional Silicon in more Computing power.

 The difference in rumored specs is bigger than in the PS3 to 360 and this time around Sony has basically just stronger but architecturally identical parts.

For MS to change right now would mean atleast 6 months delay. The system is perfectly balanced its useless to change one thing without changing everything else. GDDR5 would be not much use for a weaker Gpu and the Esram would cost Billions and wouldn't be necessary.

They would have to take out the 32 Mb Esram and add a new Memory Controller change Ram types and beef up the Gpu to make use of the Ram bandwith. 

If MS hasn't changed their stuff months ago before Sony came with 8gb GDDR5 and GDDR5 Chips increased their capacity its too late to redesign everything.

I think that one realistic option for MS would be to take out 4  Jaguar Cores of the APU and use two APUs instead of one. This way it would be 1.8  Tflops vs 2,4 Tflops and 64 MB Esram .  32 Rops vs 32 Rops, 18 vs 24 CUs.

But I think MS won't care to change anything the power difference is substantial between PS4 and 720 however most consumers don't care enough for graphics that this will matter much. Xbox was also clearly superior but people still bought PS2s.

Next time just post a DBZ picture please

I like how you keep passing of rumours and speculation off as facts, wait for the official announcement before you start pretending like you actually own a up to date Durango devkit.

I'm not saying you're wrong, it could be right, I'm saying you have no actual proof of the full and up to date Durango specs.