This type of fanfiction concept is really out of the ordinary. Naruto's character is built on his values of friendship, loyalty, and his dream of becoming Hokage. Killing Sasuke would mean betraying all of that. However, in a fanfiction, the author might be exploring the 'what - if' scenario. For example, what if Sasuke's actions against Konoha were so heinous that Naruto felt he had no choice? But still, it's a far - fetched and very different view from the original Naruto we know.
Perhaps they are forced to leave due to false accusations or being framed for something they didn't do. This could create a situation where they feel they have no choice but to leave Konoha in order to clear their names and also protect the village from the real threats that might be lurking in the shadows.
One possible plot development could be Naruto leaving to find a way to prevent Sasuke from ever wanting to leave in the first place. He might embark on a journey to discover the root cause of Sasuke's hatred and try to resolve it from afar. This could lead to Naruto meeting new characters who have insights into the Uchiha clan's past and Sasuke's state of mind.
At first, their relationship might be a bit rocky. They both have strong personalities and different ways of doing things. But as they face challenges together, they start to understand and respect each other more. Their bond grows stronger as they rely on each other for survival.
One possibility is that they go on a journey of self - discovery. Away from the constraints of Konoha, Naruto and female Sasuke might explore new jutsu and powers. They could encounter new enemies and allies, and perhaps form a new ninja group that operates outside the traditional shinobi village system.
Often, a theme is the breakdown of the Naruto - Sasuke relationship. Since Naruto leaves Konoha, it's a huge shift. And the Sasuke bashing can stem from the idea that Sasuke didn't do enough to support Naruto or keep him in Konoha. Maybe Sasuke is shown as being too prideful or cold - hearted in these fanfics. Another theme could be Naruto's search for a new purpose outside of Konoha, away from Sasuke's shadow.
Sakura would be extremely affected. Instead of constantly worrying about Sasuke leaving, she'd be focused on Naruto. She might feel guilty that Naruto left because of Sasuke. Her relationship with Sasuke would also change as she might blame him in some way for Naruto's departure.
Konoha would initially be in shock. Naruto is a hero to many in the village, and his sudden departure with Itachi, who was once considered a traitor, would cause a lot of unrest. The villagers might start to question the leadership of the village, wondering why Naruto left and if there was something they could have done to prevent it.
Sasuke might initially be shocked. He has always seen Sakura as someone connected to Konoha, so her leaving would be unexpected. He could be concerned about her safety, especially if she leaves without proper preparation or protection.
Another reason could be that he witnesses corruption or unfairness within the village leadership. If he sees that the system is rigged against certain groups, including himself or his friends, he could grow to hate Konoha and decide to leave.