I'm not entirely clear what you're trying to get at, so apologies if this is unrelated.
I think Sony realized they lost something special by not seizing on the Souls franchise after Demon Souls and allowing it to go to Bandai Namco (and furthermore, multiplatform). Bloodborne was a successful attempt at bringing the team back to Playstation.
As for Nioh, I look at is as an irrelevant parallel. Sony only swooped in late, after a decade of development that probably saw the game change drastically once Souls became popular, which probably only happened because it's looking more and more like Japanese devs are starting to disregard Xbox development altogether, even if they aren't directly in bed with Sony.
Ultimately it's pretty safe to say that the Souls series did indeed instigate a new genre, though it's too early to know just how to define the boundaries of it. Is it some exact cocktail of stamina meters, calculated difficulty, granular leveling, collecting 'souls' (or analogues) after each death, etc? In the case of Nioh, the answer is probably yes to all of those things, considering they're all present in a game by a completely different team, but not enough games with those exact mechanics have come forth yet to suggest that they're representative of a new genre, or if Nioh is just directly reacting to one game. It's just too early, and I don't see anything on the horizon that's doing it again.
