If they saw the future, perhaps Naruto would see himself failing to save Sasuke. This could make him change his approach towards Sasuke, trying to understand his friend's pain more deeply and find a better way to bring him back to the right path. They might also foresee new and powerful enemies emerging, and start to search for allies or new jutsu to counter them.
They might see the destruction of their village and work hard to prevent it. For example, they could start training more rigorously or form new alliances.
If Naruto sees a future where he and Sakura are not as close as they are in the present, he might start to distance himself from her, thinking it's for the best. Or on the other hand, he could try to change the future by being more open and communicative with her. Also, with Sasuke, if he sees a future where Sasuke is in more danger than he thought, he would redouble his efforts to keep Sasuke safe and this would likely deepen their complex relationship.
Naruto's future - seeing ability could completely shift the power balance in the story. He could use it to find out where all the powerful artifacts or secret techniques are hidden in the future. For instance, if he saw the location of the Sage of Six Paths' hidden power, he could get there first and gain that power. This would put him in a much stronger position than his opponents, and might even change the political situation in the ninja world as different villages would react to his new - found strength.
In this fanfiction, perhaps Hinata sees a future full of danger for Konoha. She then has to figure out a way to prevent it, with Naruto by her side. It could be that they face new and powerful enemies that they've never encountered before. She might see different possible outcomes depending on the actions they take in the present.
Well, they might see a future where they have a big family. Since Naruto always wanted to be acknowledged and have people around him, he could see himself surrounded by his children and Hinata in a happy home. And for Hinata, she might see herself as a strong kunoichi, still supporting Naruto in his Hokage duties.
One common plot twist could be that Naruto sees a future where his friends turn against him, but then discovers it was an illusion created by a new enemy. Another might be that he sees a future where Konoha is destroyed and has to find a way to change that fate. Maybe he sees a future where he becomes a villain himself and has to struggle to prevent that from happening.
Their relationship could become stronger. If Hinata sees a future where they are together and happy, it might give her more confidence in their relationship in the present. She could be more open with Naruto about her feelings.
One interesting plot could be Naruto seeing the future destruction of Konoha and having to figure out how to prevent it. He might see an enemy that he's never faced before, like a powerful new ninja clan from a far - off land. Another plot could be Naruto seeing his future self turn evil due to some unforeseen circumstances, and he has to make sure that doesn't happen. Maybe he sees a future where all his friends die and he has to change the course of events to save them.
Sasuke, on the other hand, might be more conflicted. He has his own goals and ideals. If he saw a future that didn't align with what he wanted, he might first question the vision. But ultimately, he could also take steps to change it, especially if it involved the safety of his village or his loved ones like Naruto or Sakura. He has a complex personality, so his reaction would not be straightforward.