Heh, so the graphics are essentially the same and no new modes or next-gen features were announced, but by announcing that the past-gen versions aren't planned anymore, that's a good thing because "cross-gen is holding everything back"...?
There would have been no difference between this being current-gen-only now or if it had been announced as current-gen exclusive when it first revealed itself as a title in production. It's the same game. Maybe they did run into some troubles getting aspects to run on the old boxes like they say, but most likely the main reason PS4 and Xbox One versions were canceled was because it's planned to be a multi-year-running project and they didn't want to bother with two more SKUs of diminishing interest to support and get approvals on. (Technically, that could also include more advanced DLC or Seasons that couldn't scale down easily, ala Destiny, but we'll see if it gets there.) PS4 and One product sales are tapering off (you already see some products releasing on PS5, Xbox Series, PC, and no past-gen but also yes to Switch,) and for a GAAS launching at the end of 2022 to have two aging platforms to deal with, likely that will not make sense by the time this game gets running. You the gamer won't notice much difference, and it's not because it was made with a "cross-gen engine" and they couldn't make it better with all the PS4/One baggage they saddled it with; it's because it's a 2021 product pushed to 2022 and that's where technology generally has been on this type of hardware.
I know everybody has their hopes up for a big "true next-gen" explosion, and there are certainly technologies on the horizon which will put distance past what's doable now, but I think you're setting yourself up for disappointment if you're expecting every game to visually appear a whole generation ahead soon just because they stop with any cross-gen releases, Jaguar Cores or otherwise...