Before the beginning of last gen, we had random comments from the big architects of graphics engines like Carmack, Sweeney, etc.. Despite these "clues" about next gen, people ignored them and continued with the wishful thinking. Once they were released and time got over the initial "perceived" hype, gamers realized how weak the hardware really was. This warranted possibly going back to the drawing board (or even more likely the devs complained and Sony/MS began development on stronger hardware).
Game dev kits always ship with beefed up PCs that are available only on big spenders. The kits are used to iterate on subsystem kernels, bus speeds, memory architecture, etc.. The game engines are designed around the HOST hardware and ported to the TARGET platform. If you want to get an idea of the best case scenario of hardware on the next-gen platforms, look at the highest end PCs.
The games that came out like UC, Horizon, RDR, TLoU2, BF5, Gears, etc.. all still had known rendering limitations hence still relying on baked rendering pipelines. There is no amount of speed from a CPU, SSD or 64Gig of RAM that's going to make games that use RTX a viable alternative to the built-in performance of the dedicated hardware supporting RTX.
It seems to me from reading the threads that many are putting all their hopes on the larger RAM, faster HDD access, and beefier CPU as the way to bridge the gap to getting next-gen visuals that compare to RTX. I'm sorry but this is simply never ever going to be the case. A faster streaming memory subsystem for pulling in assets quicker to show the city of Spiderman isn't next-gen. The developer would have been able to do that on a current PC. I have strong conviction that this new gen is going to play catchup with having the following features that the previous gen just couldn't do (despite the custom 1st party game engines): 16x anisotropic filtering -- yay!, full 4k resolution that eliminates the need for any kind of fancy reconstruction, faster loading times with much larger levels, much higher FPS other than the 30FPS cap, higher end graphics features like better shadows, more shadow casting lights, more animation, etc.. To me, that's a much more realistic expectation.
While that is going on, the PC games will move the goalposts a little further with RTX while the consoles will start to get a taste of it for the next-next-gen.
Hardware is always the limiting factor for production.. never ever will it be the algorithms or the art.
