Well, it could lead to chaos in the Hidden Leaf. His friends like Sasuke might go on a vengeful rampage. They would be filled with rage and guilt, thinking they could have prevented it. The village would also be in turmoil, as Naruto was their hero and a symbol of hope.
Well, Sasuke would be furious. Naruto was his rival and also his friend. He would seek vengeance on the mob without a second thought. Shikamaru, on the other hand, would be more calculating. He would try to figure out how such a thing could happen and what the long - term consequences for the village would be.
A plot could revolve around the power vacuum left by Naruto. The Leaf Village is in disarray, and other villages start to make moves against it. Pain might realize that killing Naruto wasn't really what he wanted in the long run, as it led to more instability. Or maybe a character who was in the background in the original story steps up to try and fill Naruto's shoes. They struggle to gain the respect and power that Naruto had, while also dealing with the grief of his loss.
In a fanfic where Naruto gets killed by Pain, it's a dark turn of events. The story would then likely focus on how the remaining characters cope. For example, Kakashi might feel a great sense of guilt for not being able to protect Naruto. Hinata would be heartbroken. Moreover, the Nine - Tails would be left without a host, which could also lead to all sorts of problems. The ninja world would lose its most prominent symbol of perseverance and friendship, and it would be a very different world from the one we know in the original Naruto story.
Well, if Naruto is attacked by a mob in fanfiction, it could lead to some interesting character development. He could use this situation to understand the common people's fear or misunderstanding of him better. Maybe he'd try to talk to them in the middle of the fight, like he did with Pain, to make them see his point of view. And depending on the nature of the mob, he could also discover new threats or allies within the group.
Naruto could use his Rasengan to create a big enough explosion to scatter the mob and then make his escape. He might also use his speed to quickly dash through the crowd and find a hiding place.
Hinata would be devastated. She has always had deep feelings for Naruto. She might lose all hope and become a shell of her former self. Also, Kakashi would feel a great sense of guilt. He was Naruto's teacher and protector in a way. He would probably question his own abilities and actions that led to this situation. And for the village as a whole, it would soon realize the mistake they made when they face new threats without Naruto to protect them.
It could be Orochimaru. He has always been interested in dark and forbidden jutsus. He might have found a way to create the 'mob of the dead' situation to test his new powers or to capture Naruto for his own purposes. He could use his snake - like minions along with the undead to create chaos.
One possible plot could be that the Naruto characters are trapped in a prison-like dimension similar to the mob of the dead setting. They have to fight against zombie - like creatures that are somehow related to dark chakra. Naruto could use his shadow clones to outwit the hordes, while Sasuke uses his Sharingan to detect the weaknesses of these strange foes.
One possible scenario could be a power imbalance. Maybe Sasuke discovers some new, extremely powerful jutsu that Naruto has no defense against. For example, a jutsu that can nullify Naruto's chakra or attack his spirit directly. Another possibility is a miscommunication or a breakdown in their relationship. If Sasuke believes Naruto has betrayed him in some way, his anger could lead him to kill Naruto. However, this goes against the core of their bond in the original series.