Scoobes on 02 November 2012
I doubt the PS4 will have only an APU. It doesn't make much sense as the integrated GPU would just bottleneck the entire system for its primary purpose.
As it's not coming out until at least late next year, they may well go for a custom APU that uses the GCN architecture but couple it with an actual GCN GPU (say a 7750-7770) and crossfire the two. I believe AMD were planning an APU that uses GCN next year anyway so it wouldn't be that much of a shock.
