> Should be much more powerful then any proposed Cell derivative.

That depends on the definition of "Cell derivative". I suspect most people would have called 32 SPEs servicing two or four trimmed POWER7 cores, all packed together in a chip named PowerXCell 32ii or PowerXCell 32iv, a "Cell derivative". I'd say the inclusion of the SPEs is what makes a Cell a Cell. Thus any number of SPEs servicing one or more trimmed POWER8 cores, all packed together in one chip, would be called a "Cell derivative" by most people as well, I guess. That said, it's interesting to think about whether non-trimmed POWER8 + SPEs would be percieved as POWER with added SPEs or rather as Cell with POWER PPE ;-)

> The only negative to this is the attendant increased complication
> creating optimized code for any CPU coupled with SPEs.

At least compared to current Cell chips there would be no such increase. And regarding the PPE an out-of-order core requires less optimization than an in-order core ;-)