sorry, I didn't help.
I should've reworded my response as i think it's relevant to Scorpio, as in how much difference can you expect to see, and compared to if game was made from ground up, etc
the specs is what determines it
I'm not sure that is the case. Just because something is designed for a more current generation of hardware, doesn't mean it won't still run on a previous generation of hardware.
Just look at every single game released on PC since the new generation of consoles was released. Many of them are a marked upgrade over games released prior to the relatively large jump in graphics fidelity, etc. Yet all those games can still run on hardware that is 4+ years old (similar to the 3-4 year theoretical cycle of consoles going forward).
Why do I mention PC? Because it's relevant to this thread. Just because development focuses on the latest generation of hardware or in some cases future generations of hardware (Crysis 1 on PC) does not mean it won't run just fine on far older and far less powerful hardware.
Lets go back to Crysis 1. It was for all intents and purposes a rather large generational leap graphically over anything that had come out prior. At the time it released it could not run at max graphical fidelity on the most powerful hardware that existed at the time at playable frame rates. Yet at the same time, it could run at playable framerates on hardware much older than the generation of hardware that was available when the game came out. It would be multiple generations of hardware before Crysis 1 could run at max settings at playable framerates.
Granted Crysis 1 is a rather extreme example. It was designed for PC hardware that didn't appear due to CPUs suddenly hitting a brick wall with regards to power and speed prior to the game releasing and hence not continuing to scale upwards at the rate it had been doing for many years.
However, if an extreme case can show the relative ease of supporting hardware that a game is not targeting and is massively inferior to the hardware specifications that the game was targeting, then it should be relatively simple for modern developers to scale their games across a wide range of hardware.
The only time this may become difficult is if the programming paradigm changes significantly as in the case of the introduction of Dx12 in the PC space. Where to take full advantage of Dx12 it has to be designed for Dx12 and not just be a Dx11 rendering path with Dx12 bolted on. But even when games start to be designed for Dx12, there will still be a Dx11 rendering path, it just won't be as optimal.
TL: DR - Designing a game for current generation hardware does not in any way mean it won't run on significantly older generations of hardware at playable frame rates. If programmers can make it scale across multiple generations of hardware on PC, I fail to see why they couldn't do so on consoles. Especially when there is no significant departure with regards to hardware capabilities as has existed in the console space up until now. This is assuming PC derived hardware in consoles going forward, and thus hardware capabilities of GPUs and CPUs progressing in a similar to way to how it's been on PC..
Regards,
SB