The marauders would probably have to adapt their way of thinking. In the future, the concepts of right and wrong, good and bad might have shifted. They'd need to understand these new perspectives to fit in.
They might be shocked by the advanced technology. For example, seeing flying cars and instant communication devices everywhere could leave them in awe.
One possible plot could be that the Marauders use a time - turning device by accident and end up in the future. They might be shocked by the advanced technology and different social norms. They could also meet their descendants or versions of themselves that are very different from what they expected.
Well, if the Marauders time travel to the future in fanfiction, they would first have to deal with the cultural shock. The future society might have very different values and social norms. They would also encounter new forms of magic or maybe even a world where magic and technology have merged in ways they couldn't have imagined. And their relationships with each other would likely be tested as they adapt to the new environment.
When the Marauders travel to the future in a fanfiction, they may meet the students of Hogwarts in that future time. These students could be very different from the ones they knew in their own time. The Marauders might also come across future wizards and witches who are experts in new areas of magic that the Marauders have never even heard of. Additionally, they could meet people who are working on projects to preserve the history of the wizarding world, and these people might be very excited to meet the Marauders who are a significant part of that history.
Well, if the marauders time - travel to the future in fanfiction, they could encounter their descendants or people who know their stories. It would be a strange experience for them. Maybe they would use their magic in unexpected ways in this new and different world. They could also get into trouble as they might not understand the laws and regulations of the future.
Their relationships could become stronger as they face the new and strange future together. They would rely on each other more in this unfamiliar setting.
In this fanfiction, it could be that the future has a new Dark Lord. The Marauders are brought forward in time to stop this new threat. They face challenges like understanding the new forms of magic and technology that the future Dark Lord has harnessed. They also have to deal with the fact that the future wizarding world has different social and political structures. They might start by infiltrating the Dark Lord's lair using their Marauder's Map - like skills, but find that the map doesn't work as well in the future, leading to all sorts of interesting and dangerous situations.
Perhaps the Marauders watch the future and are shocked to find out that some of their group won't survive the upcoming wizarding wars. They might then start to take extra precautions and train harder to change that future. They could also see new friendships and alliances being formed in the future that they then try to encourage in their own time.