If Naruto Gaiden was a person it would be a forty year old alcoholic, living in the squalor of its burnt out shell, still repeating all the mistakes it made when it was twenty and smelling faintly like cheap tequila and regret.
Look, the plot with Sakura’s kid what’s-her-name where she doesn’t know who her real parents are—that is Naruto’s story, which Kishi already fucked up. You have the chance to explore the world of Naruto from a completely different perspective, why the fuck would you go back to the same fucking people and the same fucking story? Also you can’t make Sasuke or glasses-girl-Karin interesting, and you can’t make them together interesting, you just can’t. They are black holes of story and intrigue, whenever the plot hands them something it’s just like, I’m not suicidal but I sure would like to kill myself.
The big problem with Naruto Gaiden, of course, is that it’s so fucking directionless. It’s not driven by a plot or even character tension right now, because the only character tension is from Sakura’s kid what’s-her-name and she’s terrible. The plot is like Kishi reading what critics write for once and saying, screw you, I have money, because seriously, another person who shouldn’t have the sharingan has the sharingan? We have only been here nine hundred times before, how thrilling. At this point you might as well give out sharingan to everybody, one creepy eye for you, another creepy eye for you and I swear, Naruto is like, the only manga where we can have a whole fucking arc about contact lenses.
Anyway the original series also followed adolescents, but it was interesting because Naruto was a kid who had to deal with complex situations and emotions he barely understood and had zero guidance for, but who had to do it anyway. He was lonely, which made him act out, which only confirmed other people’s suspicion, which made him even lonelier. He was supposed to be terrifying, but he was the worst at anything he did, and that, that is complication and complexity.
Sakura’s kid what’s-her-name has to deal with none of that, and look, it’s very common for kids her age to feel like they don’t belong in their own family, but there is nowhere near enough interaction between her and Sakura to justify it. If Kishi wants to have these kids angst, he needs to be willing to make Sakura and Naruto and their friends flawed parents. Hell, he needs to be able to write compelling parent-children dynamics, not just orphan them all or have the parents be out of the picture like he always does. Does that make sense?
Tl;dr everything about this is a bad idea