There could also be a shadow organization that has been secretly manipulating events in the ninja world. Now that Naruto has become the 'god of blades', they see him as an obstacle to their long - term goals. This organization might have agents in different villages, and they use underhanded tactics to try and take down Naruto.
It could be a new group of ninjas who oppose Naruto's new - found power as the 'god of blades'. They might be jealous or see him as a threat to their own power - hungry plans.
Perhaps an old enemy returns in a new form. For example, Orochimaru could come back with some new experiments related to blades and try to steal Naruto's power for himself. He would be a formidable antagonist as he is very intelligent and always looking for ways to gain more power.
It could be dark ninjas who oppose Naruto's new role as the God of Nature. They might want to use the power of nature for their own evil purposes, like creating disasters to gain control over regions.
Another antagonist could be a powerful and corrupted legendary Pokemon. It could be causing chaos in the Pokemon world and Naruto would have to use his skills and the power of his Pokemon team to stop it. This would be a great challenge as legendary Pokemon are extremely powerful, but Naruto has his own set of unique abilities that could give him an edge.
Another possibility is that the very entity that bestowed god - like powers on Naruto has an ulterior motive. It could turn out to be the true antagonist, using Naruto as a pawn in its grand scheme. This entity might be manipulating Naruto to cause chaos in the ninja world so that it can feed on the negative energy or fulfill some other dark purpose.
The Akatsuki could still be the main antagonists. Even though Naruto is the'son of god', they might see his power as a threat to their own goals. For example, Pain might believe that Naruto's new - found status will disrupt the cycle of pain and suffering that he wants to maintain in the world.
The shinobi clans that uphold the status quo could be antagonists. They fear that Naruto's chaotic power and new ideas will disrupt their way of life. They might try to stop him by any means necessary, including forming alliances against him. They are so entrenched in their old ways that they can't see the potential benefits of Naruto's changes.
It could be other shinobi who envy Naruto's new - found connection to the primordial god. They might see his power as a threat to their own status and ambitions, and thus try to undermine or even kill him.
Often, Naruto himself is likely to be one of the main characters. He might be drawn to the power of the Blades of Chaos and try to use them for the good of the village.
There could be other ninja villages that see Naruto's new powers as a threat. They might form alliances to oppose him, fearing that he will use his god - like abilities to dominate them. Also, there might be dark forces or ancient evils that awaken because of Naruto's transformation. These entities could oppose him as they try to maintain the balance of power in their own dark ways.
Well, the main antagonists could be a group of rogue ninja who are hired by a powerful nation to take down Naruto. Since he is unkillable, they would have to use more underhanded tactics like trying to isolate him from his friends and allies. Or perhaps there is a dark force that is awakened by Naruto's unkillable state, thinking that he is a threat to the balance of the ninja world. This dark force could then become the main antagonist, trying to destroy Naruto at all costs.
Maybe some of the more malevolent Greek gods could be antagonists. If Naruto's presence disrupts the balance of power among the gods, some of the jealous or power - hungry ones could try to get rid of him. For example, Hades might see Naruto as a threat to his domain and try to stop him from interfering in the affairs of the underworld.