The lack of a beacon signal also indicates something: either a hard impact or a safe landing in the north or a quick sinking in the south. A sinking in the South makes more sense to me.
If it's sitting on the ground somewhere in central Asia, and there were no further Inmarsat calls because the power was turned off, I'm sure a radar difference image between three weeks ago and two weeks ago would have been able to show it up.
How many places with a 777-sized hangar to hide it in are there in central Asia?
There would seem to be no prospect of survivors, so the only issue is whether the causes can be determined.