I too am greatly saddened by the loss of this boy, I can think of little that is more terrible than this. My heart goes out to this child, his family, his unit and his friends.
The buddy system is all important and this story is so moving that it will be a topic for one of our unit meetings. I have significant wilderness experience / training both BSA and non BSA, so I can give a lot of advice even for adults.
Even adults should have a buddy when traveling in the wilderness, and particularly when traveling in the back country a minimum of four to six adults should be present. Wilderness trained adults are a must when traveling with children. Back country registrations should always be filled out and submitted to the appropriate agency. Whistles are great, but of little use to an injured non responsive single person.
When hiking as a unit, leaders must enforce trail discipline - expelling children from the hike for repeated failure to abide by safety rules - one strike for a serious offense, and offenders are then marched out under adult supervision to the pickup/dropoff point where they will remain under supervision. These rules must be spelled out clearly in advance. One primary rule for trail hikes - the unit moves at the speed of the slowest individual! Slowest boys in front, fastest boys in back - forced to go slow by the unit pace. A leader ALWAYS is placed in the rear and the front of the unit. Any buddies that go off by themselves without leader approval, or singly by themselves will stand before the entire unit to explain the transgression. If this sounds harsh, then consider the alternatives - which indeed happen. Parents / Leaders - lead by example - you too must have a buddy. This scout was not alone in this kind of peril - these kinds of losses have happened before to both scouts and private citizens.
There is nothing to compare with back country hikes and climbs, but always 'saftey first' - OR NO TRIP! Leaders must PLAN for emergencies. What do we do if ...? how can we get immediate assistance (radio / satellite cells / adult runners) ... BSA is a great place to learn, but ultimately the adults are responsible!
BSA should consistently deny trip permits for lack of appropriately trained leaders and suspend units for safety / permit infractions.