The New Ham kids will find other societies eventually
If Pfeiffer is truly the Pied Piper of legend, then it's possible he's done this before to other towns across the country, or even the world, and they all exist in this dimension. What kind of societies they find depends on how things work there—they might find the original German children trapped in time, or a society where everyone's grown into an adult, or simply the remains of one who's children couldn't make it and killed each other off. Campbell will die in season 2
As terrifying as he is, every one seems to be aware of it now. All they need is one good moment of clarity to take him out. The only question that remains is who. Lexie will stay mayor in season 2
Despite her attitude when campaigning, the end of season one seems to imply that she's realized Allie's rules were the only thing keeping things sane, even if people were starting to dislike them. Whether the others in charge are able to be deposed or not, Allie will trust Lexie to make the right call after seeing what a dictatorship looks like. Becca will become mayor in season 2
If the kids overthrow Campbell's group and demand an entirely new government, they'll want someone who has a vested interest in keeping the peace and providing for others. Becca fits that to a T, especially with baby Eden in tow. His co-conspirators will get exposed as frauds who planned the coup, but Campbell will still be a Karma Houdini by the end of Season 2
Given that Campbell is a Magnificent Bastard and The Sociopath, he won't hesitate to throw the people he manipulated to his side under the bus when it seems like the new leadership might fail. Not to mention the people who helped him will endure a worse backlash, because everyone already knows Campbell is not trustworthy. Not to mention most of the townspeople believe Lexie and Harry are in charge, so even if they try to blame him, he can deny it and be convincing enough for people to believe him, and even spin it to where he is a convenient scapegoat and gain sympathy from the townspeople. There are half of the teens of West Ham who are still with there families and/or used to live there but have moved out before the series began.
Since the teenagers were moved to New Ham, possibly not all of the teenagers were taken there because they did not participate in the senior class trip that sent the current ones to New Ham. There are most of them who are still with there families and are busy moving on with their own lives in a normal way while their friends are stuck in a never-ending battle of power or there are some who moved to West Ham or have stayed there for a week/month unaware that the new friends that they wanted to meet are not here. It's possible that there might be teens between the ages of 13-15 or 18-23 who will find out about what happened with their friends/family members. Allie's storyline mirrors Ned Stark's
From Game of Thrones. They both reluctantly take over leadership roles early in the story. They're both overshadowed by their leader of a sibling, but forced to take charge after their untimely death. They both tend to value morality and the common good at the expense of their own political situations (or even their safety). They both embody the mantra "the man who passes the sentence should swing the sword." They both have a political rival in their grasp but let them go. That rival arrests them and falsely accuses them of trying to steal power. At the end, they're both brought before a jeering crowd that throws rocks at them. Mercifully, Allie doesn't meet Ned's fate in that scene. Campbell will severely torture Allie, physically and mentally to the point where she might end up having amnesia as a result.
Knowing how much of a psychopath and manipulator Campbell is, he will viciously torture Allie now that she is under his captivity, for possibly 2-6 months. Later, Allie might get saved by Elle and others. But due to too much bodily and psychological damage, she might suffer from amnesia. Because of that, she won't be able to remember key events from Season 1, especially Cassandra's death and her executing Dewey. The teens will be rescued from New Ham by the end of Season 2, but Allie will run away from the country and change her identity and Season 3 will have a time jump that focuses on their separate adult lives.
The teens will be saved by the time Season 2 ends with Campbell being arrested on multiple charages (kidnapping, terrorism and extortion) and sentenced to SHU for 50-60 years while the members of the Guard get a lighter sentence as accesories (community service, 1 year jail time, probation etc.). But unfortunately, the expirience, especially being imprisoned by Campbell, has traumatised Allie for life. This causes her to get out of USA entirely and move to another country assuming a new identity, fearing that despite the actual law taking care of Campbell he will manipulate them again like he did with the Guard and escape and go after her. Then there is a Time Skip of 8-9 years focusing on the now grown up characters and how they've been dealing with their New Ham trauma, most importantly what has become of Allie ever since she disappeared from the US.