I seriously doubt we'll be seeing any style other than the hyper-stylized "toon" look cell-shading technique Ninty has co-opted to cover for their utter lack of technical proficiency. I think Nintendo simply lacks the technical know-how to develop for modern visual standards, hence their insistence on cell-shading. And Ninty doesn't even do cell-shading well. Visual flair is not the reason anyone plays a first party Nintendo product. Which is a shame because it's the reason I play Zelda (or used to, anyway).
Who's to say what the situation will be for video games by the time Nintendo gets around to the next main series console Zelda (at least half a decade, minimum except for Majora's Mask) or if Nintendo will even be in it (yes, imagine a world without Nintendo is a distinct possibility)? I would have gone through (and hopefully survived) my midlife crisis by then. But perhaps Nintendo will finally have hardware up to modern standards by that time. Even still, it doesn't seem like they're even interested in selling hardware on its technical specs or developing graphics for it. The toony style is here to stay. And I think we can abandon all hope of Witcher 3 quality graphics out of Nintendo anytime this decade.
I think the only reason Nintendo would ever have to return to the more grounded style of Twilight Princess is if they wanted to make a game marketed exclusively for western sensibilities- which Twilight Princess really seemed to be.