We know a 777 disappeared over the ocean and we have not found the crash site. Any reasonable speculation at this point as to why is impossible.
It took two years to get the answers for AF447. The shallow water near their last known position will make this one much easier. The black boxes will tell the story when they are found.
The media wants to keep public interest up with scraps they have like stolen passports but nothing will be known until the FDR and CVR are recovered.