Is the rumored software backward compatibility real?

[sieanr]

HappySqurriel said:

Being that Microsoft designed both the XBox and XBox 360 to use DirectX (which acts as a hardware abstraction layer) the XBox 360 only has to emulate the XBox's CPU and can "Translate" all of the calls to DirectX and let the XBox 360's GPU handle it.

 

And this is a big part of the reason why many Xbox games aren't on the BC list yet. Any game that went around DX to get as close to the metal as possible, and thus the best performance possible, are going to be nearly impossible to emulate properly. This is especially true of the games which took advantage of hardware quirks, or undocumented hardware behavior. Since these things are generally only known to the developers getting it emulated properly is going to require a very accurate low level emulation or figuring out what the hell the developers did. 

Now my understanding of the PS2 is that this situation is even worse. Since Sony had absolutely terrible dev kits early on many developers started using the hardware in ways it was never intended to be used. This is something that not only happened with shovel-ware developers, but also top-tier studios squeezing every last ounce of power out of the PS2 - stuff like GOD2, BLACK, or the Rise of Neo (which had normal mapping). Using undocumented or flawed behavior requires the emulator to be very, very accurate at duplicating the behavior of the original hardware. Sometimes these exploited flaws are so minute that hardware redesigns will actually prevent games from playing correctly, and this actually happened with the PS2. 

In other words a practical PS2 emulator that works with most games would have to written very well at a low level. To get good performance it would likely have to be a high level emulator. Since these two are incompatible its likely that there won't be a pure software PS2 emulator on the PS3, or it will be of low quality. 

Furthermore Sony is focused on profitability, and I can't see the justification for spending tons of money on BC when they are outselling the 360. In addition surveys have shown that few people use BC on systems that offer it, and those who do generally own the previous system.