I've always said that FB should work with authorities and bring in a system that's connected to missing child alerts (The Amber alert system in the US).
Authorities could have access to send out "Amber alerts" and FB users in the 'target area' receive a notification via FB.
It would require users to have entered their home location and/or have location sharing enabled.
It will fail like their other apps such as Slingshot. They should focus on their own apps and services. What happened to them? At the very beginning, Facebook was really good, each year getting a redesign and new features. Right now it feels dull and with that Messenger away from their app, it is absolute crap. They have WhatsApp now.. Why the need for another?