Sasuke might initially be indifferent on the surface, but deep down he would feel a sense of loss. He has always had a rivalry with Naruto, and Naruto's departure would mean an end to that dynamic. Sakura would be devastated. She has grown to care about Naruto as a friend and teammate, and his leaving would leave a big hole in the team.
The popularity of 'Team Seven Naruto Fanfic' comes from the fact that the characters of Team Seven are so well - loved. People want to see different scenarios involving them. For example, they might want to see how the team would handle a certain difficult mission that wasn't in the original anime or manga. Also, fanfic writers can give their own interpretations of the characters' development, which is very appealing to fans.
One possible plot development could be Naruto leaving due to a misunderstanding. For example, if he is wrongly accused of a crime within the team. Another could be that he feels he is holding the team back in some way and decides to leave on his own to become stronger alone. Maybe he has a personal goal that he believes he can't achieve while still being part of Team 7.
One great 'Team Seven Naruto Fanfic' is 'The Bonds of Team Seven'. It delves deeper into the relationships between Naruto, Sasuke, and Sakura. Another one could be 'Team Seven's New Missions' which creates interesting and unique adventures for the team. And 'Team Seven: Beyond the Canon' is also quite popular as it explores what could have happened outside the original storyline of Naruto.
In this type of fanfiction, Naruto leaving Team 7 can be a very emotional and plot - twisting scenario. It might lead to Hinata stepping up to support Naruto in different ways. For example, she could be the one to convince him to come back to the team eventually. Also, this situation can explore the deeper feelings between Naruto and Hinata as they are forced to deal with the change in their dynamic.
Sasuke might become more withdrawn. He was always in a sort of rivalry with Naruto, and without Naruto there, he could lose some of his motivation to get stronger. Sakura would be devastated. She cared about Naruto, and his leaving would make her question what went wrong. Kakashi would also feel a sense of failure as a teacher.
One common theme could be the re - imagining of the characters' personalities in a more negative light. For example, making Naruto seem more self - centered instead of his usual selfless self. Another theme might be changing the power dynamics within the team, perhaps making Sasuke seem weaker than he actually is in the original story.
In such a fanfic, Naruto might become extremely lonely and start to doubt his self - worth even more. He could potentially go on a journey of self - discovery alone, away from the village that has shown him so little love through the actions of his team. Maybe he would find new allies who truly understand him and help him grow stronger not just in terms of power but also in terms of his emotional stability.
There could be a fanfiction where Team Seven is brainwashed or under some sort of mind control. As a result, they turn on Naruto and attack him. This would be extremely hurtful to Naruto, both physically and mentally. He would be confused as to why his friends are suddenly trying to harm him and it would shatter his trust in them.
One possible reason could be a conflict within the team. Maybe Naruto felt misunderstood by Sasuke or Sakura. Another reason might be a mission gone wrong where Naruto blames himself and decides he's a liability to the team. Or perhaps he gets an offer from another group that he believes can help him achieve his goals faster.