One possible plot development could be that Sasuke is in a life - threatening situation, perhaps against an extremely powerful enemy. Naruto sacrifices himself to give Sasuke a chance to escape or defeat the foe. This would likely lead to Sasuke being filled with guilt and regret, and might change his whole outlook on life.
In such a fanfic, the plot might begin with a rift between Naruto and Sasuke that has just started to heal. Then, a new threat emerges that targets Sasuke specifically. Naruto, being the selfless hero he is, jumps in front of an attack meant for Sasuke. His death could then send shockwaves through the ninja world. Sasuke might be haunted by Naruto's last words or the look in his eyes. He could then go on a journey of self - discovery, trying to figure out how to honor Naruto's sacrifice. This could involve him trying to bring about the peace that Naruto always dreamed of, while also dealing with his own grief and guilt.
One possible plot development could be that Hermione is left with a deep sense of guilt and responsibility. She might then take on Harry's mission or cause in his memory. For example, if they were fighting against a new dark wizard, Hermione could become even more determined to defeat the enemy.
One possible plot development could be Naruto having to deal with Sasuke's relationships. For example, he'd have to interact with Sasuke's friends in a different way than Naruto would normally. He might also discover new things about Sasuke's past that even Sasuke himself was not fully aware of. And Naruto's own skills and abilities might be affected by being in Sasuke's body, leading to some interesting battles or training sessions.
Well, perhaps in the 'naruto vs sasuke the aftermath fanfic', there could be a focus on the physical and mental recovery of both Naruto and Sasuke. Naruto, being the more positive of the two, might bounce back quickly, but Sasuke's internal struggles could be explored in depth. There could also be new threats emerging that they have to face together, which would force them to put aside their differences and cooperate, even if reluctantly at first.
I haven't come across a particular 'naruto dies saving sasuke fanfic' myself. However, you might want to check Naruto - centered forums where fans discuss and share such stories. Maybe by asking around in those communities, you'll find what you're looking for.
One possible plot development could be that his friends are left to pick up the pieces. They might struggle with grief and guilt, thinking they could have saved him. Another could be that Voldemort finally takes over completely without Harry to oppose him, leading to a dark reign over the wizarding world.
One possible plot development could be that the Hidden Villages struggle to maintain peace without Naruto's influence. His death might lead to power vacuums and political unrest. For example, some villages may try to take advantage of Konoha's weakened state. Another aspect could be how his friends and family cope. His wife, Hinata, might have to raise their children alone, and his friends like Sasuke would feel a great sense of loss and perhaps guilt for not being able to protect him. The ninja world as a whole could also lose its hope symbol, and new, darker forces might emerge, thinking that without Naruto, they can carry out their evil plans more easily.
One possible plot could be that Naruto and Kakashi are in a fierce battle against a powerful enemy. Kakashi is about to be fatally attacked when Naruto jumps in front of him and takes the hit. As Naruto is dying, he might have some final words for Kakashi, perhaps about the importance of protecting the village and their friendship.
Perhaps there's a prophecy involved. The fanfic could be set up where it's foretold that Boruto will bring about a great change, but only if he survives a certain threat. Naruto, aware of this, sacrifices himself to ensure Boruto lives on. This could then trigger a series of events where Boruto has to deal with the political fallout in the village, as some may blame him for Naruto's death, while others see him as the key to the future. It could also lead to a rift between Boruto and some of his friends who struggle to understand why Naruto had to die for him.
The other demigods at Camp Half - Blood would also be in chaos. Percy was like a leader to many of them. His death could lead to a lack of confidence among the younger demigods. Some might even start to question the protection of the gods. Zoe's survival could also lead to her taking on a more prominent role in guiding and protecting the demigods, which is a big change from her previous situation.
One possible plot could be that Fem Haku has some sort of unique ability or knowledge that is crucial for the safety of the Hidden Leaf Village. Naruto and Fem Haku are being pursued by an evil organization that wants to stop her from reaching the village. Along the way, they face numerous obstacles and battles. In a final showdown, Naruto realizes that the only way to ensure Fem Haku's survival and the safety of the village is to sacrifice himself. He gives his life to protect her, and Fem Haku then has to deal with the consequences of his death, like facing the villagers who may blame her, and also has to figure out how to use her abilities to protect the village on her own.