He would have become incredibly powerful and likely been a major force in protecting the universe.
If Gohan never stopped training, he could have surpassed Goku and Vegeta in strength. His potential was always huge, and continuous training would have unlocked it to a great extent. Also, he might have taken on more leadership roles in battles against powerful foes.
Well, if Gohan kept training, he'd likely become way stronger and could handle even tougher opponents.
Well, if Lee was never bitten, the entire course of the story could have changed drastically. Maybe he wouldn't have gained the powers or abilities that came with the bite, and his role and actions throughout the fanfiction would be completely different.
Well, one possibility could be a fanfiction where Gohan faces a new, powerful enemy that forces him to keep training constantly to stay ahead.
If Kenshin never made that vow, the character's development and his relationships with others might have been very different. He might not have had the same internal struggles and growth that make him so compelling.
Gohan could gain better control over his emotions during training with Whis. This is important because in battle, a clear - headed fighter is more likely to succeed. Whis could teach Gohan how to stay calm under pressure, which would enhance his performance in fights. Also, Gohan may learn some unique moves that are exclusive to Whis' training regime.
If Anakin hadn't turned, the Sith's plans might have been foiled. The balance of power would have remained with the Jedi, and galactic conflicts could have been avoided or resolved differently.
Well, the galaxy would have been a much more peaceful place. The Jedi Order might have remained strong, and there would likely have been no rise of the Empire.
Well, for one, the Lannister influence might not have been as strong. Also, the fate of Robert's children and the succession to the throne would likely have changed drastically.
Well, if Jon Snow never took the black, his path would have likely been very different. Maybe he would have stayed at Winterfell and had a greater role in the affairs of the North.
The theme of isolation also pops up. Sometimes, Gohan isolates himself to train, away from his loved ones. This gives him the space and focus he needs, but also creates internal conflicts as he struggles with the loneliness that comes with such intense training.