AC: Valhalla could be 60 fps easily on the next gen console, even in lower resolution... but it won't.
And you know why?
Not because the developers are lazy.
Not because the new consoles aren't powerful enough.
But because 60 fps is a PROMISE.
A promise that all the next AC titles will also be 60 fps.
Because once you go 60 fps in a cyclic series, there's no turning back.
And it's not an easy promise, especially for open-world games.
Can you imagine that after so many years another Call of Duty only go for30 fps? What a flame on all medias it would be.
No, go back to the year 2013 when AC: Black Flag came out.
This cross-gen title could also run on PS4/XO in 60 frames. Easily.
But it didn't, for a simple reason.
Because Ubisoft already knew at that time that with the more ambitious projects they were planning for AC: Unity and later titles like AC: Origins/Odyssey, they wouldn't be able to deliver 60 fps for the current generation.
Can you imagine how much AC:Unity and later AC:Origins/Odyssey would have be downgraded if they had to deliver 60 fps on the current generation?
Yeah. And it would even have a negative impact on sales if these games were graphically much worse than other titles from competition aiming for 30 fps.
And Ubisoft knows very well that it doesn't matter that they have now enough power to make AC: Valhalla to run at 60 fps on next-gen,
But they also know well that 60 fps target would very limits the ambitions for truly next-gen Assassin's Creeds.
So, that's why do I think that Ubisoft (and many other companies,) do not want to close the 30 fps door so they can deliver much more ambitious things in the future, and the promise that all sequels game will also be always 60 fps, may just not be accomplished.