I believe that engines like Unity, Unreal, CryEngine, Frostbite et al could spend some of their resources on optimizing for hardware at a lower level, and are also the greatest benefactors of being able to experiment.
That's not to say that they will - other factors are at play too. But it's possible. There's a big gap between the power of a PC GPU and the performance it delivers, and narrowing that gap would certainly make PC more competitive with consoles, which in turn could make it more worthwhile for developers to optimise for specific PC hardware 'models', creating a spiralling effect.
That's not to say that they will - other factors are at play too. But it's possible. There's a big gap between the power of a PC GPU and the performance it delivers, and narrowing that gap would certainly make PC more competitive with consoles, which in turn could make it more worthwhile for developers to optimise for specific PC hardware 'models', creating a spiralling effect.