The reason I think he will be found is because it all (IMO) seemed to go down on Wednesday morning before 5:30. (yeah, I know, Einstein am I) Or late Tues night. According to the babysitter the boyfriend called her at 5:30 am to say she wasn't needed that day at 6 am, which was extraordinary not to need her. If the mother didn't notice he was missing until 9 am, why was the sitter canceled? Probably, IMO, 5:30 was the earliest he could call her, reasonably, also meaning to me that something could have happened any time after the sitter brought him back on Tuesday, but probably some night time event. Police will know by now whether or not boyfriend who called sitter really went to work, and who was in that house. I think it happened quickly and he/she/they had to get rid of Q and didn't have many places to go. IE not well thought out. (Sorry). Apparently there were 3 adults in the house that night, early morning, just survival of the fittest means that one will squeal on whatever happened, even if just to confirm that Q was able to open door, etc, which I don't believe. Maybe the other little boy, maybe a neighbor saw movement.
All IMO!!!!
If he is found in a pond, and without injuries it could be seen as an accident from his "walking away"