Once a missing person has been gone for three or four months, what is there to do? People talk about searching, but unless the person or a body is found in the first few days, usually it becomes a matter of waiting for a break.
For example, Chelsea King's body was found quickly. That led to an arrest and the subsequent finding of another young girl, Amber DuBois, whose body was found far from the point of abduction. Although her parents believed that she was taken to that area by car because of a search conducted by dogs, her body was not found until the suspect was identified.
My point is that people who abduct and kill are almost always one or two steps ahead of the families and LE because they know what they did and where and how they did it. At some point, the dedication of massive resources doesn't make any sense, because a missing person who has been murdered or taken from the area and hidden could be anywhere. LE in this case clearly concluded that the stepmother is responsible for Kyron's disappearance, based in part on what we know but no doubt on evidence turned up in their investigation that we are not aware of. If LE is right, it won't take a giant, multi-jurisdictional task force to get justice; it will more likely be the efforts of the prosecutor, who will make a case, bring charges, and perhaps force a plea deal. Someone who knows may feel pressure to talk--or perhaps already has under the secrecy of the Grand Jury.
Another possibility is that the body will be discovered by some ordinary person going about his or her business (hiking, hunting, etc.) and that will provide both forensic evidence and a location that may suggest or eliminate suspects. If Kyron was murdered, he may well be in a place that has already been searched, only too well hidden to be found.
The other possibility is that LE got on the wrong track from the beginning, following TH, who certainly looks like a good suspect. That can happen, even given the best of efforts by LE. If the investigation narrowed too soon, it will take the discovery of the body or some other break we can't foresee to find out what happened to Kyron.
The only reason I can see for a task force is if Kyron's disappearance is part of a criminal conspiracy that covers multiple jurisdictions. If a tip comes in that Kyron, whether or not he is still alive, can be found (let's say) in California, of course LE in that jurisdiction would help until the tip was resolved. So why would there be a need for a task force? My larger point is that "searching" is not the same as "investigating," and at some point, it makes sense for the case to be investigated like any other crime, because once a person has been "missing" for months--what else can anyone do?