There would be a power shift. Since Madara was extremely powerful, Naruto - as - Madara would be an almost unstoppable force. Other villages would have to either ally with Konoha (which would be a difficult decision considering the situation) or try to find a way to counter this new threat. This could lead to a new arms race among the ninja villages.
The balance of power between the different ninja clans would also be disrupted. The Uchiha clan, which had been on the brink of extinction, would suddenly have a new figurehead in Naruto - as - Madara. This could lead to a resurgence of the Uchiha's influence, and other clans might feel threatened and start to take preemptive actions, which could further destabilize the ninja world.
One possible way is through some sort of powerful jutsu gone wrong. Maybe a forbidden jutsu that was meant to do one thing but instead warped Naruto's being and made him take on the form and some of the characteristics of Madara Uchiha. It could also be the result of some dark magic or curse that was placed on him by an enemy who wanted to disrupt the balance in the ninja world.
If Naruto becomes Madara Uchiha in fanfiction, it could drastically change the plot. Firstly, the relationships would be turned upside down. Naruto's friends might see him as an enemy, especially Sasuke who has a complex relationship with the Uchiha legacy. The power dynamics in the ninja world would also shift. Naruto, with Madara's power and knowledge, could either rule with an iron fist or try to reshape the world in a more extreme way compared to his original goal of peace. And the Akatsuki's plans would likely be disrupted as Naruto, in Madara's form, might have different motives regarding the tailed beasts.
If Naruto and Madara become friends, it could completely change the power balance. Their combined strength would be a deterrent to any potential invaders. On a more positive note, it could inspire a new generation of ninjas to look beyond past grudges. The younger ninjas would see that even the most bitter enemies can become friends. This could lead to a more unified ninja world where different clans and villages work together more closely. For example, the Uchiha clan might regain more trust within the Leaf village, and other villages might be more open to sharing resources and knowledge.
One of the most interesting aspects is the character transformation. Seeing Naruto, who was always full of hope and positive energy, take on Madara's dark and brooding persona. It's like a complete 180 - degree turn. Another aspect is how the other characters react. For example, Hinata might be completely lost, not knowing how to deal with this new Naruto. Also, the power - up Naruto would get as Madara. He would have access to the Sharingan and all of Madara's combat skills. It would be exciting to see how he uses them in battles, especially against opponents he used to face as Naruto.
One major change would be in the way the village is perceived. Naruto is well - known across the ninja world, so other villages might see his village as even more powerful and stable. This could lead to a shift in the balance of power. His village would likely attract more talented ninjas who want to learn from him.
Madara would have to adapt to the different threats in RWBY, mainly the Grimm. In his world, he was used to fighting other shinobi and clans. The Grimm are a whole new type of enemy. However, his Sharingan would give him an advantage in detecting their movements. He might also try to find a way to use the Grimm's negative energy, similar to how he used negative emotions in his own world to fuel his power.
Their combined abilities would likely make them the most powerful entity in the ninja world. For example, Naruto's ability to sense negative emotions and Madara's combat experience could lead to a new form of justice. They could easily defeat any rogue ninja or group that threatens the peace.
If Naruto saved the Uchiha clan, the story of the Hidden Leaf Village would be rewritten. The history of the Uchiha's massacre would no longer be a dark stain on the village's past. The Uchiha would contribute their unique skills and abilities to the village's development. For example, their Sharingan abilities could be used for better security or in battles against common enemies. There would also be a change in the relationships between characters. People who were once enemies of the Uchiha might have to learn to work with them.
The village would likely be in chaos. Naruto has been a key figure in protecting the Hidden Leaf. Without him, there would be a power vacuum, and enemies might see it as an opportunity to attack. The villagers who once relied on Naruto would be filled with fear and uncertainty.
No. Naruto has his own unique story and character development that is distinct from simply being a fanfiction of Uchiha Madara. Naruto is about his journey to become Hokage, his relationships with his friends like Sasuke, Sakura, etc. His goal is to bring peace to the ninja world in his own way, through understanding and friendship. While Madara is an important part of the Naruto lore, Naruto's story is not centered around being a fanfiction of Madara. He is his own hero with his own dreams and challenges that are not directly related to being a fan of Madara.