The current Cell processor design is pretty much dead. SPEs do not make sense anymore and IBM knows this. The new generation of Cell processors will be a few Power7 cores that manage a few thousand stream processors. Even if they call it "Cell", it is a completely different architecture. Granted, it will definitely borrow a few technologies from the current cell, but it will simply be a different processor with the same name.
This those effect the PS4, as it means that backwards compatibility is pretty much dead. If developers thought that porting games to the cell processor was bad, they are going to struggle even more with stream processors. Emulating a Cell with stream processors + a few cores is not hard, but it requires more power than will be available in the next generation of consoles.
Good news Everyone!
I've invented a device which makes you read this in your head, in my voice!