I think the big question is what the scope of their projects will be moving forward.
I always thought it strange that some folks here think a linear Halo campaign could not possibly be made to work between consoles generations.
We don't know much of what MS has planned after Infinite, but I think we can assume Forizon Horizon 5, Fable, and Gears 6 will follow.
There's Hellblade 2 as well, and though I'm sure it'll show off the technical prowess of the Series X, a linear action game shouldn't be too daunting a challenge to downgrade. Remember, that Switch port of Hellblade is supposedly solid considering the gulf in power.
Maybe Fable is where the cut off happens. We'll see.
Hellblade 1 was incredibly limited in scope and you were only ever fighting a few enemies at a time. If the sequel is similar with just jacked up visuals then it's not even relevant to this discussion.