God of War has always been a Sony exclusive hasn't it? It's like firing up your PS4 expecting to be able to buy Halo.
I'm not familiar with the series at all so didn't know that, I was just watching review videos (in Edge!) about how amazingly awesome the game is whilst I was down in the kitchen cooking, and decided I'd buy it.
I'm not sure who wins really, it's not like I'm going to get a PS4 Pro just to play God Of War, so Sony neither sell me a copy of their game, or one of their consoles.
The daft thing is that the PS4/XB1 and PS4Pro/XB1X are very similar in hardware terms so it'd be a pretty simple port job.