In a time - travel scenario, Sasuke could learn from different eras. Say he travels to a time of great peace in the ninja world. He would be exposed to different values and ways of life, which could soften his cold exterior. He might start to value friendship and cooperation more, as he sees how effective they are in maintaining peace.
One idea could be Sasuke traveling back to the Uchiha massacre. He might try to prevent it, which would completely change the Naruto storyline. This could lead to him having to face off against Itachi in a different context, not as an avenger but as a protector of his family.
Luke and Solo were the two main characters in the Star Wars series. They were all heroes of their youth who had experienced many setbacks and growth. Luke longed to fly and escape from the planet that bound him. He planned to join the Imperial Military Academy. Han Solo also yearned for the life of a pilot, and his path also pointed to the Empire. They all wanted to become pilots and draw their own destiny in the starry sky. Luke's performance was relatively gentle, while Han Solo was a hooligan who was the most important to his survival. They had a complicated relationship in the series, sometimes friends, sometimes enemies. The story of Luke and Solo played an important role in the Star Wars series.
Yes, there might be such fanfics out there. In the Naruto fandom, with a large number of fans creating various types of stories, it's possible that some would write a story where Naruto destroys Sasuke in a way that could be seen as Sasuke - bashing. However, these kinds of fanfics may not be in line with the overall spirit of the original work which focuses on their complex relationship and growth.