Its been my experience that 99.9% of crimes are motivated my either sex, drugs or money.
I don't think this case involves sex. Would be extremely rare for a child molester to kill two people in order to abduct a girl. Its just too easy and less risky to do it in other ways. I will say that I still do consider an unknown boyfriend to be a viable theory though.
It really doesn't seem like this family had a lot of money, however what is nothing to some people may be a lot to others. The family, although they didn't live extravagantly, did seem to keep their daughter busy with extracurricular activities, so they definitely weren't poor. We know the husband had worked Sunday, could this have been a "cash" side job that somebody had found out about? A possibility. But then again, why would they take Jayme?
Drugs don't seem to be an issue with this family, not users, not sellers. However the area seems to have a big meth problem and there is always the possibility that some type of crime is going to occur when those people are around. However, I just don't see how blasting the guy that opens the front door is going to be beneficial, and I don't see why burglars would take a hostage.
So, of these three scenarios, only one (sex) would give me reason to think Jayme may be still alive. I just can't fathom any kind of reasonable scenario as to why someone in search of drugs or money would take the girl? And, if by chance they had some hair brained scheme as to what they were going to do with her, surely the attention this case has brought would have caused them to abort those plans, which wouldn't be good for Jayme.