Sure we'll notice improvements. It's just that people expect to much from DX12. And yes, Sony can improve PSSL. Tey're already doing.
The 41% advantage (Xbone GPU clocking higher) is another thing though. That basically is what leads to resolutiongate. Or a bit more GTA grass. And that basically is it.
Oh, and i don't have a PS4, just Wii U and One. So no intention to let Xbox look bad.