Major unmarked spoilers ahead. Read at your own risk.
Grover will become an experiment.
In season 1, Grover comes across a picture of himself, labeled "Retrieval Target". His parents work in Keller Chemical, and in season 2, it has been confirmed by Barrett that Grover's dad is a part of Project Wednesday, which includes turning normal people into experiments. For examples on experiments, see Jake and Birdie.Sadie will turn.
Sadie reported to Diesel that she has a dry mouth and she feels weird. The same symptoms appeared with Mary before she turned into a freak.Hailey will turn.
Hailey is the last human to leave the room trying to save her girlfriend, Birdie. She was also not wearing a mask when she left the room, which may imply that she breathed in the contaminated air the longest.Zane will turn.
Despite being dragged out of the room by Diesel, he showed the most resistance after holding Violet's corpse. He was also not wearing a mask when he left the room.No one will turn.
It is possible that a) Birdie may have just had a grand-mal seizure unrelated to any nearby freaks; or b) there's a freak inside the cafeteria.Everyone inside the school will die or turn freak before they get rescued.
It is implied that one or several people will turn freak, so maybe they will turn and kill the rest of the remaining students. Or, maybe several people die from other ways. It is inevitable that people will keep dying throughout the course of the show, but who dies is the question. Grover will be the only survivor at the end of the show.
There's something weird about him. He should've been able to turn freak because he inhaled the contaminated air to prevent his death, and he was never in danger because he's a retrieval target. He may have been born solely to become an experiment, and Mary is the only person that wasn't intended to become an experiment.- This excludes Jake and Birdie.
Alternatively, Barrett will be the only survivor at the end of the show.
Excluding Jake, Birdie, and other experiments, Barrett will eventually survive the genocidal apocalypse and expose Keller Chemical, and also the horrors of what happened after the chemical spill, in a series finale. Besides Grover, he is one of the only survivors who knows what really happened inside the chemical company, and about Project Wednesday.Ollie is eventually killed by someone/something else.
Ollie will eventually get what he deserves for leaving his sister behind and escaping on the helicopter.The vault will lead to an underground escape route, away from the valley.
Hoping that the school survivors live long enough, they will open the vault and discover a secret escape route. The vault looks like it hasn't been opened for several decades, and someone died trying to open the vault.The vault is a dead end.
The vault may have nothing to offer. It hasn't been touched in decades.The vault will lead to Keller Chemical.
It is possible that the Keller family may have built the vault so that survivors who have come across it will lead to the company building.The vault has nothing but old documents, or money...or both.
It could be possible. Not saying it's impossible.The construction company that the corpse once worked for built the vault.
Whether the vault is an escape route or a dead end, it's there and it holds a lot of mystery. The construction company may have been the ones to build it. The corpse may have been trapped not because he was forced in there, but because he went inside and the door closed by accident.The school was built before or during the Cold War.
Fallout shelters historically appeared during the Cold War in preparation for a nuclear war or a chemical issue. It may not have to do for Keller but also for a general nuclear war.