Yeah but that's not any different then the cross platform games which were on both PS3 and PS4 for a good few years after this gen began. We had cross platform games up till 2015 as a norm and Persona 5 released on PS3 in 2017.The same games are supposed to work across both iterations. It doesn't exactly extend the generation. You just have to pay much earlier for incremental upgrades now, a slowly progressing PC if you will.
Sure the difference in OG PS4/XB1 games to Pro/XboX may never become as large as cross platform but it serves the same purpose. The biggest question is do you guys think PS5/XXXbox will need to support Pro/XboX games or not ? That's gonna be the more interesting thing to tackle. Will we even see a new 'generation' or will consoles become iterative ? Pro can run PS4 games but no guarantee Pro Pro will need to have PS4 backward compatibility.