I never heard that Sony was planning on re-instating backwards compatibility. Would you like to share the source?
Furthermore, it's not possible to upgrade your PS3 for backwards compatibility (the original launch units actually had the Emotion Engine chipset built in). Furthermore, software emulation seems extremely unlikely due to the complexity of the PS2/PS3.
If Sony does ever release a PS2 software emulator it will rip a hole in the space time continuum.
Ah, sorry. I might have misread your statement. Did you mean you need specific models in order to make your PS3 run again? I've never heard of someone splicing parts but I highly doubt it will work (someone correct me if I am mistaken).