As of now, Naruto and Sasuke haven't died in the Boruto manga. Their characters continue to play significant roles and contribute to the story's development.
One emotional moment could be when Sasuke first realizes how close Naruto is to death. His face might show shock and fear, which is a big deal for someone as stoic as Sasuke. Another could be when Sasuke vows to Naruto that he won't let him die, with a really intense look in his eyes. It shows the depth of their bond.
Another scenario could be that they are poisoned by a new, undetectable toxin. As they gradually weaken, they try to find a cure but run out of time. Their deaths would be a great loss, and it could lead to major changes in the political and social structure of the ninja world as everyone copes with their passing.
Sasuke's determination serves as a major driving force. It might force him to use his skills and powers in new and creative ways. He may have to face his own limitations and grow stronger in order to keep Naruto alive. This growth could be both in terms of his ninja abilities and his emotional maturity. As he tries to save Naruto, he could also be forced to confront his past actions and make amends, which would be a big part of the plot development.
The emotional impact on the readers can be intense. Fans who have followed their journey from the start would feel a great sense of loss. It's like seeing two great forces that were meant to be rivals but became friends, disappear. There would be a lot of sadness, but also a sense of respect for their sacrifice if it was for a noble cause in the fanfic. It might also make the readers think about the themes of friendship and sacrifice more deeply.
Sakura would be completely devastated. She's been in love with Sasuke for so long and has a deep bond with Naruto too. She might go into a deep depression and lose her will to be a ninja for a while.