> a Power derived Cell is a complete unknown.

True, assuming you refer to real products and assuming you mean POWER here, not Power ISA in general. As we established before in this thread, both the PowerXCell 32ii and PowerXCell 32iv were suspected to come with PPEs derived from POWER7.

> Sony's potential use in computing devices would be, at least, a small return.

Only if such new Cell with POWER-derived PPE is going to act as the CPU of (at least some of) Sony's future notebooks. As you may remember, when Toshiba was said to have Cell technology in their notebooks all they eventually released were some models in their Qosmio line with the SpursEngine (i.e. only SPEs, no PPE) acting as a video coprocessor chip for the x86 CPU. We'd have to see if Sony's ambitions in that regard would be more serious or if they would replicate Toshiba's way regarding notebooks containing technology based on a new Cell.

> the next Cell processor used in the PS4 could easily benefit from IBM's developments.

That's a given, no matter if the new Cell's PPE will be derived from IBM POWER or be any other Power Architecture compliant core developed by IBM. One of those two options would be realized for a new Cell for sure.