I said the same thing when BotW first came out: it's one of the greatest video games ever made, with a great foundation to become even more spectacular. TotK unquestionably achieves that, but part of me feels like refinement and iteration can never feel as special as those first moments playing the first open world Zelda on a brand new console. I have a nagging suspicion that some/many reviewers will find this also, and mark the game down for being exactly what we all wanted it to be.
Sure, they can add more clever, expansive content/functionality to the game, and keep fleshing out the world's characters/stories, but at times, TotK feels indistinguishable from BotW, and I feel like another successor would feel the same.
TotK somehow takes what was, pre-Elden Ring, my favourite video game of all-time, and makes it better in every possible way. But somehow it feels less special because of it's iterative nature. But the new content is incredible and makes the world so much more enjoyable to explore. Does that make sense? Anyway, it's an amazing, amazing video game and likely to be a lot of people's GOTG/GOATs...just not mine, and that's okay, because I got exactly what I wanted.