AFAIK, SoC isn't related to low power consumption alone, nor performance. Like the guys said, stick a CPU, GPU, IMC, and any other chips/controllers/etc into one chip and it'll be a SoC -by definition- regardless of how much power it draws or how much flops it can crunch. ARM will still pwn the business as it currently has the best power consumption. But that's for the Mobile segment. A PS4 is more of a PC.