One possible plot could be that Naruto sacrifices himself to protect Sakura from a powerful enemy. Maybe he uses a forbidden jutsu that drains his life force but saves her from certain death. Sakura would be left in shock and grief, and this could lead to her seeking revenge against the enemy or trying to find a way to bring Naruto back, perhaps through some ancient ninja magic.
In the fanfiction, it might be that Naruto is poisoned during a battle and by the time he gets to Sakura, he's on the verge of death. He tells Sakura his final words, like expressing his unspoken feelings for her or his hopes for the village. Sakura, being a medic - ninja, tries desperately to save him but fails. This event could then change the whole dynamic of the story, with Sakura becoming more withdrawn and determined to change the ninja world in Naruto's memory.
Perhaps Naruto is poisoned by a powerful new villain. His parents are revived just in time to see him succumb to the poison. This event could trigger a series of events where his friends and the entire village vow to avenge his death. His parents might then decide to stay in the living world to help in this quest for vengeance, despite the rules of the afterlife.
One possible reason could be that she sacrifices herself to save Naruto from a powerful enemy. In the heat of battle, she might put herself in harm's way to ensure Naruto's survival.
One possible plot development could be that Sakura's tears somehow give her a newfound strength or resolve. Maybe she decides to train harder to protect Naruto in the future. For example, she could seek out a powerful teacher or a hidden jutsu to become stronger.
One possible plotline could be during a powerful enemy attack on the village. Sakura might sacrifice herself to save Naruto and the rest of the village. Maybe she uses all her medical chakra to heal a large number of injured villagers while fending off the enemy at the same time, but in the end, she exhausts herself completely and succumbs to her wounds.
In this fanfiction, it could be that Naruto's death as a baby is the result of a conspiracy. Maybe some anti - Uzumaki or anti - Jinchuriki group within Konoha planned his death. This would then lead to a series of events where the truth is slowly uncovered by some of the more perceptive characters in the village. This could create a lot of internal conflict as characters have to choose between loyalty to the village and uncovering the truth about Naruto's death.
One possible plot could be that Naruto dies heroically in a great battle against a powerful enemy. Then, he is reborn into a world that is very different from his own. He might retain some of his past memories, which help him to quickly gain strength and knowledge in this new world. He could use his new - found situation to prevent the same tragedies that occurred in his previous life.
In this kind of fanfiction, one possible plot could be that Naruto loses all his friends due to some unforeseen and tragic events. Maybe he makes a great sacrifice to save the village, but in the process, he becomes estranged from everyone. His friends might misunderstand his actions, or he could be cursed in a way that drives people away. Eventually, he dies alone, with his heroic deeds forgotten by most.
One possible plot development could be that Sakura is deeply affected by Naruto's sacrifice. She might vow to carry on his will and become even stronger. In the story, she could use Naruto's death as motivation to finally achieve peace in the ninja world. For example, she could take on Naruto's dream of uniting all the villages and work towards it with all her might.
Well, I'm not sure about a single highly recommended one. But in general, in these fanfictions, Naruto's death for Sakura can lead to many different plot developments. It could make Sakura stronger, or it could drive a wedge between her and other characters who might blame her in some way for Naruto's sacrifice.
In this fanfiction, Naruto's death could be a sacrifice. As a hollow, he could start off being very confused. His ninja skills might be warped in this new form. For example, his Rasengan could turn into some sort of dark energy blast. He might also meet other characters from the Naruto world who have also had strange after - deaths, and together they try to find a way to either move on or return to their normal state.