No, it's not expensive. The graphics synthesizer chip (the difference between the 80gb and the 40gb) is known to cost less than $30, and probably less than $10. Most of the remaining cost savings in the 40gb come from shrinking the cell processor, and consequently putting in a cheaper power supply and less cooling hardware. Future PS3 models will have these same revisions.
Jack Tretton himself admitted that BC wasn't dropped to save money, but to stop people from buying PS2 games for their PS3s. It was a stupid reason to drop BC then, and it's even stupider now.
I think there's almost no doubt that this model will be backwards compatible. Even ignoring the more obvious arguments, it would be awfully hard for them to justify the $100 price difference without it.









