It could be some rogue ninjas who target Sakura because of her relation to Kakashi. They might think they can use her to get to him or extract information from him.
Danzo might be an antagonist. He's always been power - hungry and might see Naruto as a threat, especially if Kakashi is guiding and protecting him. Danzo could try to undermine Kakashi's efforts to raise Naruto and might even send his root agents to spy on them or cause trouble.
Orochimaru could still be an antagonist. He might see Naruto as a threat especially if Kakashi is training him intensively. His goal of obtaining power could lead him to target Naruto.
It could be a new group of rogue ninjas who oppose the ideals of the Hidden Leaf Village. They might target Kakashi's daughter because of her connection to Kakashi and Naruto, seeing her as a symbol of the village's new generation of strength.
One potential antagonist could be some pure - blood supremacists who don't like the idea of Harry Potter having a half - blood or Muggle - born daughter. They might try to cause trouble for Lemon at Hogwarts or in the wizarding world in general. Another could be a dark wizard who sees Lemon as a threat for some reason, perhaps because of her special abilities or her connection to Harry. They would try to harm her to get to Harry.
Yes, there's a fanfiction called 'Sakura: Kakashi's Legacy'. In this, Sakura inherits Kakashi's unique jutsu and fighting style. It shows how she struggles to live up to his reputation while also forging her own path. It's a great read for those who like to see family - like relationships in the Naruto universe.
One potential antagonist could be a rogue ninja who also has aerokinesis but uses it for evil. He might be jealous of Naruto's natural talent and try to undermine him at every turn. Another could be a powerful sorcerer from a far - off land who has come to the Naruto universe specifically to find someone with aerokinesis to either steal their power or use them as a tool. There could also be a group of anti - ninja who see Naruto's new power as a threat to their plans of overthrowing the ninja system and they try to eliminate him.
The village elders could be antagonists. They might see Naruto and Kakashi as threats to their traditional way of ruling the village and use false accusations to banish them.
A plotline could revolve around Sakura getting special training from Kakashi. He could pass on his unique skills and knowledge, like his lightning - style jutsu or his stealth techniques. This would make Sakura an even more formidable ninja and also strengthen their father - daughter bond.
Perhaps Orochimaru could still be an antagonist. In this fanfiction, he might be jealous of Naruto's new god - like gaming powers and try to steal them for his own experiments.
There could be a jealous fellow ninja from within the village who feels that Naruto is getting too much attention for his blade - mastery. This ninja could turn against Naruto and become an antagonist, perhaps even teaming up with external forces. Also, an ancient evil entity that was sealed away long ago might be awakened by the power of Naruto's blade and seek to destroy him and the village to regain its freedom.