His old team would be Sasuke, Sakura, and Kakashi. They are the main characters associated with Naruto's early team experiences. In the context of this fanfic where they die, it's likely to have a huge impact on Naruto and the overall story.
Naruto would likely be devastated. His old team was an important part of his early life in the ninja world. He might initially go into a state of shock, unable to believe that they are gone. Then, his grief could turn into anger, vowing to find out who was responsible and make them pay.
Well, in a 'sakura dies saving team 7 fanfic', the plot could go like this. Sakura might be in a situation where Team 7 is facing an overwhelming threat. She could put herself in harm's way to buy time for Naruto, Sasuke and Kakashi. For example, if they are being attacked by a group of powerful ninjas, Sakura might use her chakra - enhanced strength to create an opening for the others to flee. And in the end, she succumbs to her injuries while the rest of Team 7 is saved.
It could be some of the younger ninjas from the village who look up to Naruto. Maybe a young genin who has a special ability with earth jutsu, and another who is really good at stealth but lacks confidence. Naruto would then help them grow.
Yes, there might be such fanfics in the vast Naruto fanfic community. Some fanfic writers like to create alternative scenarios where the characters' identities are swapped or unexpected events like the main character's death occur. These fanfics often explore different aspects of the Naruto universe and the characters within it.
The villagers themselves could be responsible. Their constant ostracization and negative treatment of Naruto could lead to his downfall. He might be pushed to a point where he takes risks that ultimately cost him his life.
Sasuke would likely be devastated. Despite their past differences, Naruto was his rival and in a way, his closest friend. He might go into a deep state of regret and isolation. Sakura would be heart - broken. She loved Naruto, and his death would be a huge blow to her. She might become more withdrawn and focus all her energy on her medical ninjutsu. Kakashi would be filled with a sense of failure. He was Naruto's teacher, and he would feel responsible for not being able to protect him.
I'm not sure specifically as there could be many different versions of such a fanfic. But generally, it might involve Naruto facing some overwhelming danger in the Wave arc that leads to his death, perhaps a more powerful enemy than in the original story or a failed mission that costs him his life.
There could be a scenario where Naruto sacrifices himself to save Boruto or the entire Hidden Leaf Village from a catastrophic event like a massive attack by an unknown and dangerous force. He might use all his chakra to protect the village, leaving him with no energy to survive.