Colby- Depends. He would need to be in a group to survive, more because he'd need to be around people to keep his morale up enough to survive. Without a group, he'd withdraw into himself and likely end up dead.
Gale- Alive and well, though it's hard to say if she would be mentally okay. She's the easiest of my muses to drive over the edge and is the most unpredictable. I can't say if she'd take up the leadership role in a group, or would snap completely and be in "everything that comes near me dies" mode.
Atticus- Dead. Probably died protecting some of his family. Also, even if he had survived, it wouldn't last long. His clumsiness and lack of practical survival skills would do him in quickly.
Shawn- Alive, either on his own or with one other person. His paranoia makes it hard for him to trust anyone at this point. He's still terrified of a lot of things, but instead of debilitating him, it hones his senses and drives his survival. Being a good runner also helps. Refuses to kill unless he really, really has to, preferring flight to fight. ))