It's minimal at best. Remember FFXIV is also on the PS3 so any limitations across the field is set to the weakest link, PS3. Once they reach the end of the cycle that involved the PS3. It's more likely there will be enhancements to the engine but only to what the best performance on the PS4 can handle. PC is only flexable in that you can upgrade components without having to replace the whole thing. PC's will always have the edge on that it isn't hardware locked. But at some point, (and its getting closer) you wont be able to tell the difference between a game console and PC other than spreadsheet and other office programs. Well not quite, it'll be more like a Apple since upgrading individual hardware will always be an issue for consoles.