One possible consequence is that the power balance in the ninja world is completely disrupted. With the Kyuubi's massive chakra and power running free, smaller villages might be constantly in fear of being attacked. Konoha, in particular, would have to find new ways to defend itself without relying on the fact that the Kyuubi is sealed within one of its shinobi.
If the Kyuubi isn't sealed in Naruto fanfiction, Naruto's character development would take a very different turn. He wouldn't have to go through the internal struggle of taming the Kyuubi's power within him. Instead, he might have to face the Kyuubi as an external enemy. This could lead to a more adversarial relationship between them, and Naruto would have to develop his skills in a different way to deal with this powerful being.
The presence of an unsealed Kyuubi would likely change the political landscape of the ninja world. Alliances might be formed differently. For example, villages that were once enemies might unite against the common threat of the Kyuubi. On the other hand, some might try to use the Kyuubi's power for their own gain. There could also be new types of ninja techniques and strategies developed specifically to deal with an unsealed and powerful Kyuubi.
Well, in fanfiction, the Naruto and Kyuubi fusion could lead to a change in how the ninja world views Naruto. He would be seen as an even greater threat or an even more powerful ally. For example, other villages might be more hesitant to engage in conflict with him. Also, his relationship with his friends could be affected. They might be in awe of his new power but also a bit worried about the Kyuubi's influence on him. And on a physical level, his appearance might change, perhaps taking on some of the Kyuubi's features, like his eyes or his hair color getting a more reddish tint.
Well, one reason could be that the author wants to explore an alternate universe. Maybe in this fanfiction's version of the Naruto world, the events leading to the sealing of the Kyuubi never occurred. It could be due to different political situations among the ninja villages, or perhaps a different chain of events that prevented the Kyuubi's attack on Konoha in the first place. So, without the attack, there was no need for the seal.
Perhaps a plot twist where the seal on the Kyuubi was never complete. And as Naruto grows stronger, parts of the Kyuubi's true form start to leak out in unexpected ways. This could lead to Naruto having to struggle not only with controlling the Kyuubi's power but also with hiding this new development from his friends and enemies alike, adding a whole new layer of tension to the story.
If the fem Kyuubi gets control of Naruto in the fanfiction, one consequence could be that Naruto's relationships with his friends might be strained. His friends might not trust him anymore as they notice the change in his behavior under the Kyuubi's control. Another possibility is that Naruto could be used to cause chaos in the village. Since he's very powerful, the fem Kyuubi could use him to carry out her own plans, which might be harmful to the village and its people.
One possible consequence could be chaos in the ninja world. With Naruto, a major force for peace, dead and the Kyuubi released, other villages might see an opportunity to gain power or territory. Villages that once relied on Naruto's protection would be vulnerable. Also, the Kyuubi, being a powerful and wild force, could start causing destruction on its own, without Naruto to control it.
Well, his relationship with the village could be affected. The villagers who were once afraid of the Kyuubi might be even more hesitant to accept Naruto now that he has the complete power. However, his closer friends like Sasuke and Sakura would stand by him. Sasuke might see Naruto as an even greater rival, but also a potential ally in protecting the village. And Sakura would be there to support Naruto both emotionally and in battle if needed.
One consequence could be a huge power boost. Naruto would become extremely strong, which might change the power balance in the fanfiction world. Enemies would be more cautious of him, and allies might rely on him more. Another consequence could be the internal struggle. The Kyuubi has its own will, so Naruto might have to constantly fight to maintain control when it's summoned.
Well, for the village in this fanfiction, there are several consequences. Firstly, there's the issue of security. They have to worry about the Kyuubi breaking free from Naruto. This means they might need to invest more in defenses. Socially, the presence of Naruto with the Kyuubi sealed in him can cause a rift. Some villagers might be more accepting, but others will always be fearful. Economically, they may have to spend resources on researching ways to better control the Kyuubi's power or to protect the village from any potential disasters related to the Kyuubi.
In some fanfictions, Kaguya being sealed might lead to new mysteries emerging. For example, there could be hidden secrets or powers that were associated with her that now start to surface. This could draw in new characters or lead to new adventures for the existing ones. Maybe some of Kaguya's leftover chakra starts to influence certain events or people in unexpected ways.
The balance of power in the Naruto universe of the fanfiction could be disrupted. If Bardock was a powerful force against some impending evil, his sealing could allow that evil to thrive. For example, if there was a powerful enemy that Bardock was meant to fight, with him sealed, the enemy could start to conquer and cause chaos more easily. Also, his friends or allies might start a quest to unseal him, which could lead to many adventures and encounters with other characters, both good and bad.