Granted, this is nothing more than personal speculation, but we are using history as a foundation for this hypothesis so it's not merely wishful thinking.
When the PlayStation 3 launched back in 2006, it held the disagreeable price tag of $599. Perhaps some weren't aware at the time, but the inclusion of a special graphics synthesizer chip, which allowed for nigh-on full backwards compatibility for PS2 software, contributed to the exorbitant retail price. It wasn't long – a matter of months, really – before Sony decided to remove the chip from new PS3 models and embrace emulation for PS2 software; something Microsoft does with the Xbox 360 concerning original Xbox games. This meant that rather than 98-99% b/c for the PS3, we had about 75-80% b/c, although gamers were thankful to find that most all popular PS2 titles were included in the "compatible" list. Then, Sony abandoned even that, and the PS3 would only play PS1 games and zero PS2 games. For those of you with relatively large PS2 libraries who had sacrificed the PS2 when they purchased a PS3, this came as a significant blow.
Now that you're aware of the history, let's switch gears for a second: at the start of this generation, Sony would often say that force feedback in controllers was a "last-gen feature," which is why they didn't include it in the original PS3 controller, the Sixaxis. But the fan outcry was big, and Sony eventually responded with the Dual Shock 3. Switching back to the hardware, Sony has said we shouldn't expect a price drop any time soon, although many analysts and game journalists say we should anticipate a cut this holiday season. In the meantime, Sony has issued several press releases outlining the reasons why the PS3 is worth the money; why it offers more than the competition. However, two things appear to be happening: 1. people really are clamoring for PS2 backwards compatibility to return (PS1 b/c never went away), and 2. everyone really needs a price drop. Rumors of a Blu-Ray-less PS3 have shifted around a bit, but that doesn't even make any sense .
Furthermore, the economy really won't allow for a price cut right now. Sony just managed to drop the production costs down to around $440 per machine, and they can continue to lower that number. They can do this because the cost to manufacture many of the individual parts for the machine has been slashed; new technology costs less and less as time goes on, remember? Therefore, perhaps it would be possible to assume that bringing full b/c back wouldn't cost nearly as much as before…? And if you're not going to drop the price, perhaps bringing back a beloved feature amongst long-time PlayStation fans might further prove the machine is worth the price of admission. "No, you don't need that PS2 – which still costs $129, by the way – because your PS3 will play all your PS2 games you still enjoy!" As the cost of producing the console continues to fall, Sony remains insistent that a price cut isn't coming, but for what may come as a minimal price to them and at no additional charge to you, they can really cater to their avid followers.
It's just something to consider. Backwards compatibility really may be a feature that simply won't ever return, but you never know… Nuttier things have been known to happen.