I recently went thru a schizophrenic scare with my almost 12 year old son. His counselor thought he for sure was, but his psychiatrist said that kids on the autism spectrum have to be granted more leeway in their magical thinking, because their brains are wired differently and sometimes they get stressed out to the point that they hear voices and people can suspect that they might be developing schizophrenia. My son was actually having visual and auditory hallucinations. It all stopped when his medication was changed.
He still will talk about his stuffed animals and other toys as if they are real. All his life I've gone along with him enough to not upset him but I haven't tried to make it more than it already was, if that makes sense. He'll ask about his stuffed dog, "Do you think Bowser wants to sleep on his side or on his back?" and I'll say "well I haven't seen other dogs sleep on his back so I don't think that's comfortable for dogs, so maybe just on his side." Occasionally when he's feeling more stressed I'll ask if he wants to hold or lay with one of his stuffed animals, like Perry his finger puppet stuffed parrot or Inchy his beanie baby inchworm. I'll say maybe they can help you feel better...
What I've noticed as he's gotten older is that he is not afraid to have these sorts of play sessions in front of me and including me, and that it seems like it's extra special now that he's getting older and has tough 12 year old boys as friends. It's like a safe way he can revert to needing care and comfort. I'm glad I never made him feel bad or weird about it.
For what it's worth, I know for sure that my stuffed animals (and his) are not real, but I sure feel tender hearted toward them, and I'm 46!
As for actually developing schizophrenia, the psychiatrist made sure I know that he could be autistic AND schizophrenic, but that there is no point in worrying now until things progress, as it's very rare to show up this young. And your son is even younger. Other early symptoms are covered in this article: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2930984/
I've read a bunch about it and talked to other counselors and what I've found out is that as it actually develops, most people will know that they are not supposed to admit to the hallucinations. They feel very defensive about them and know they will be considered crazy. I would think that this would mean you'd not want to discourage your son now from talking to you about his magical thinking, because you won't want him to start hiding it from you. You'll want to be able to keep an eye on how it develops. I highly doubt your son is developing schizophrenia, but I think the best way to be prepared is to not damage your relationship by making him feel he needs to hide things from you. If he is developing it, you can't make it go away by telling him the things he's experiencing are not real, but you can make him clam up about them as much as he's able, and that will make it more challenging for you.