The power balance would be greatly affected. If fanfiction gives Naruto some overpowered abilities like instant teleportation across any distance, it would make many of his battles much easier. Enemies that were once a threat would no longer be so.
The relationships in the Naruto universe could be rewritten. For example, if in the fanfiction Naruto has a different family background, his relationship with characters like Iruka or the Third Hokage could be very different. He might not have the same emotional connection to the village as he originally did.
The overall theme of the Naruto universe might shift. Fanfiction often explores different themes than the original work. If the fanfiction fused with Naruto is more about political intrigue, then the Naruto universe could become more focused on power struggles within the village and between different ninja clans rather than just the overarching themes of friendship and perseverance in the original Naruto.
Naruto would probably get Madara's Sharingan abilities. This could give him enhanced perception and the ability to copy jutsu more easily, like a supercharged version of his own ability. He might also gain access to Madara's Susanoo, which would be a huge boost to his combat capabilities.
The power dynamics could shift. In fanfiction, new powers could be introduced to Naruto, making him even more powerful. This would change how he is perceived in the Naruto universe and how he interacts with other characters like Sasuke and Sakura.
The power dynamics would shift significantly. Naruto already being very powerful, with the connection to Kaguya, he might be seen as an even greater threat or asset. Allies and enemies would likely reevaluate their relationships with him.
If Naruto was Kenpachi - inspired in a fanfiction, the ninja world would see a more aggressive Naruto. He'd be quicker to engage in combat, which could either intimidate his enemies or make some of the more diplomatic ninja a bit wary. His new attitude might also inspire some of the younger ninja to be more bold in their training and battles.
The Naruto universe would be completely desolate. There would be no more ninja villages, no more clans, and no more shinobi way. It would be a world filled with silence and death.
It would change the combat dynamics a great deal. Guns are much more powerful in terms of long - range attacks compared to traditional ninja weapons. This would mean that strategies for battles, both in the village and against enemies, would need to be rethought. For instance, the importance of cover and stealth would increase significantly.
Well, Naruto getting a Keyblade would be a wild turn. Firstly, the Keyblade has a certain magic to it. Naruto's world is mainly about chakra, but with a Keyblade, he could introduce a new form of energy. He might be able to combine chakra with the power of the Keyblade. In terms of his friends, they would be both amazed and a bit envious. Sasuke, for instance, would see it as another way Naruto is getting stronger. And Naruto would have to learn how to wield it properly. He might start training with it in the same way he did with his rasengan, trying to master all its functions and forms.
The storylines would be more diverse. Instead of the typical ground - based adventures and battles, there could be more exploration of the skies and high - altitude regions. Also, Naruto's relationships with other characters might change. Some characters might be in awe of her wings and new abilities, while others might be envious. This could lead to new character arcs and development, like Sasuke seeing Naruto's wings as another sign of her growing power and feeling the need to become stronger himself.
It would change the power dynamics. With her succubus powers, fem Naruto could disrupt the traditional balance of strength. For instance, she might be able to defeat stronger opponents more easily by using her charm and allure.
His personality could become more calculating. Since Cell is a rather cunning and strategic being, Naruto might start to think more like a tactician. He'd still have his core values of protecting his friends and the village, but he'd approach battles with a different mindset.