The other thing is if they change up the gameplay with a new type of story, they cannot integrate gameplay and story together in such a way that it hinders the game outright. This is why I think Ascension was a bad God of War, because in story, Kratos wasn't as angry and was 'nicer', but this seemed to matter in gameplay. Needing rage to do combos, instead of actually being powered up to awesome levels, is ****ing stupid and is a slap in the face. The game felt slower and lacked cohesion - in fact the story was almost non existent at times. Using only the Blades in that one with a pitiful magic system and what not only soured it worse. They simplified the game too much after II since I think in that one, people were taken off guard by how brutally hard the game could be outright, especially in the Palace of the Fates so they commonly complained and they simplified stuff so much. Auto aim for grabs, magic being tied to weapons, weapons being a variant of the blades and so on. III did a decent mix but then Ascension came and that game made you feel weak. It all seemed due to the story.
I can understand a different formula or significant changes because the most consistent complaint is God of War didn't change past II, which is dumb when you realize not only have franchises like CoD never changed, but changing up too much results in modern Sonic the Hedgehog, or even Resident Evil's current identity crisis. We'll probably see more information as development goes on, like how Kratos survived at the end of III and how he got here.