I think that if FromSoft ever tinkered with adjustable difficulty, they ought to do it like Ice-Pick did for Pathologic 2. Pathologic 2 has one core difficulty that's very clearly locked in as the game's "true" difficulty (as in the game tells you this directly). Changing the difficulty requires you to specifically opt out of the intended difficulty, and opting out at any point precludes you from getting an achievement for beating the game on that intended difficulty. If you do opt to change the difficulty, you're met with a series of sliders for specific game elements and developer commentary on when and how they recommend adjusting them, rather than just simple difficulty options.

Not only does Pathologic 2's system allow for a really great amount of player control over the experience, it also allows the game to remain balanced around one intended experience, with everything outside of that experience being condoned but still explicitly noted as not being what the game was designed for. I think something like that would map to FromSoft games perfectly well.