Yes, there are likely some fanfictions with this concept. In the Naruto universe, Naruto and Sasuke have a complex relationship. This idea of Naruto as Sasuke's sensei could lead to some interesting story developments, like Naruto teaching Sasuke new jutsu or different ways of looking at the ninja world. It might also explore how their dynamic would change from being rivals to a more teacher - student relationship.
One possible plot could be Naruto teaching Sasuke some new and unique jutsu. For example, Naruto, as a sensei, might introduce Sasuke to a special type of nature transformation that he learned during his travels. This could lead to Sasuke evolving his own fighting style and becoming even more powerful.
One possible plot is that Naruto, after achieving a high level of power and recognition, is asked to mentor Sasuke who has been struggling with his own path. Naruto would first focus on Sasuke's mental state, helping him let go of his revenge - driven mindset. He would then train Sasuke in new ninjutsu and taijutsu forms. As they train, they would face challenges from old enemies who see this new alliance as a threat. This would force them to work together even more closely and strengthen their bond.
In the fanfiction, Naruto's new sensei could be a mysterious figure who has ties to the Sage of Six Paths. This person might have been waiting for the right time to appear and train Naruto. They could possess knowledge about the origin of chakra and how to fully unlock Naruto's power. It could also be someone who was once an enemy but has now changed their ways and wants to use their skills to train Naruto for the greater good of the ninja world.
There's a chance that Naruto's new sensei could be a self - taught ninja who has developed their own unorthodox style. This person sees Naruto's ability to think outside the box and wants to refine that in him. They could introduce Naruto to a new way of looking at chakra control and combat strategies that are completely different from what he has been taught so far.
I think Orochimaru would be the most unexpected sensei. Usually, he's seen as a villain, but in a fanfiction, if he were to train Naruto, it would be extremely unexpected. He has a vast knowledge of jutsu, especially forbidden ones. He could teach Naruto some very powerful and unique abilities, but at the same time, Naruto would have to deal with Orochimaru's morally ambiguous nature.
Well, it would have a huge impact. For Naruto, losing his sensei would be like losing a father figure. He'd be deeply saddened and might feel a bit lost in his ninja journey. The other characters like Shikamaru and Kiba would also be affected. They might start to question the safety of being a ninja. And the village as a whole would be in mourning. This could lead to a change in the village's dynamics, with more caution in sending ninjas on dangerous missions.
A plot twist could be that their deaths were faked by themselves. They might have discovered a great threat to the village that required them to go undercover. So, they faked their deaths to deceive the enemy. Or, perhaps their deaths lead to the awakening of an ancient evil that was sealed long ago. And it turns out that their deaths were somehow a sacrifice to keep this evil at bay for a while, but now the remaining characters have to find a way to defeat it once and for all. This would completely change the direction of the fanfiction.
Naruto's teaching style would probably be more hands - on. Since he has always been a doer rather than just a theorist, he would likely demonstrate techniques directly to Sasuke instead of just lecturing about them. For example, if teaching a new taijutsu move, Naruto would first show Sasuke how it's done and then let Sasuke practice while he gives feedback.
One popular story could be about Sasuke and Sakura Sensei teaming up to train a group of young ninja. In this fanfiction, they might combine their unique skills and teaching styles to bring out the best in their students.