He might be really surprised. He would see all kinds of new interpretations of his world, his friends, and his adventures. Some fanfics could show him achieving even greater things in the future, which would make him feel proud. And if there are fanfics that explore his relationships in new ways, he'd be quite intrigued.
Since Naruto is an adventurous person, he would be eager to explore the different scenarios presented in future fanfic. He would be open - minded about new ideas like new jutsu or different relationships between characters.
In Naruto future reaction fanfiction, characters might react to various things. For example, they could react to new jutsu developed in the future. They might be amazed at the power and creativity behind it. Maybe Naruto himself would be excited to see how the next generation has advanced the art of ninjutsu.
A frequent theme is the exploration of character relationships in the future. For instance, how do Naruto and Sasuke's relationship evolve further? And how do other characters react to this? Also, the theme of facing new, more powerful threats together often appears. Characters' reactions to these threats can vary from determination to fear.
He might be shocked. In the fanfic, if he sees things like his friends' future achievements or the new threats that emerge, it would surely startle him. For example, if he discovers that one of his friends has a family of their own and has become a great leader in the village, he would be proud but also a bit surprised at how much has changed.
Naruto would probably be deeply hurt. He values his relationship with Sasuke so much that such a betrayal would shatter him. He might become withdrawn or angry.
There would likely be a lot of negative reactions. Fans of the Naruto series who love the original themes of friendship, heroism, and ninja values would be appalled. The Naruto fandom is quite large and protective of the original spirit of the show, so this kind of fanfic would be seen as a desecration of the characters and the world that has been created.
Hinata would probably be extremely shy at first. She might blush furiously and be at a loss for words. After all, she has had a crush on Naruto for a long time, so it would be a dream come true for her.
The baby could grow up to be a great ninja. Maybe he'll inherit Naruto's dream of bringing peace to the ninja world. He could learn new jutsus and techniques, and become a respected figure in the village.
The older characters such as Kakashi would be cautious. They would recognize Naruto but also be worried about the implications of someone from the future being in the present. They would want to know if his presence could change the future in a negative way. For example, they might fear that his actions could lead to the earlier awakening of a powerful enemy. As for the villains, they might see future Naruto as a threat and try to eliminate him as soon as possible. Orochimaru, for instance, would be very interested in Naruto's future powers and might try to capture him to study. And the new generation of ninja in the past would look up to future Naruto, seeing him as a symbol of what they could become.
Most of the fandom would probably be horrified. Naruto is known for his positive values, and killing a family member is completely against that. There would likely be a lot of criticism towards the author of such a fanfic.