I'd be worried about the teenager that actually enjoyed Speaker for the Dead.
I like the book, it might be the best of the entire series, as it deals with some actual science fiction themes and the ethical and moral complications surrounding them -- and while it takes a biased view (how could it not, being a novel), I think the bias is self-aware and not unfair. But it's such a slow, heavy read when you come out of Enders Game. The series starts to go off the rails after Speaker -- but that's just how Card series are.
No real fear of a hollywood sequel to Enders Game. You could make the Speaker movie, and it would probably be a good movie -- but who would pay to see it? Buncha Portugese biologists yelling at each other for being assholes with a white dude going, "woah -- woah" is 3/4 of the book.