PS3 had a graphic card with arround 0,24 Mflops compared to 1,84 Tf of PS4´s one. Many people said that it wasn´t much of a jump in graphics. I think it was, probably the most important factor was going from 512 MB (256 VRAM) to 8 GB for textures. Resolution jumped from HD to full HD doubling pixel count. But most people say that the jump was nothing compared from ps1 to ps2 and ps2 to ps3.
Next jump will feel even less impresive. Specially if you own a PS4 pro. Of course I´m talking about graphics. Resolution will be better of course, Ram will double or triple but not increase 16 times like from ps3 to ps4 for sure. The thing is we reached a level of good textures and good poligon count, and even if we are going to get better it won´t feel like older generation jumps in graphics.
CPU will be a different animal.
going from Jaguar cores to Ryzen cores will be masive and will allow massive worlds, better AI, better physics, and better FPS. That will be the jump to be wainting for. No doubt about it. The experience will improve a lot.
Now going back to graphics, it will be like ohh meh, its the same but looks better because it´s 4k.
Ray tracing may be implemented here or there but we still need another 10 years to get global ray tracing graphics the way it should be.
It would be fun though, I´m eager for the new gen to come up. Good CPU with 4k it´s something that I´ve been waiting for , even if RT is not ready for prime time. But it´s not a matter of hardware alone, maybe developers find ways to get better graphics with the same hardware next gen too.