I’ve been postulating a possibility for a few days, so I’ll put it out there along with all the others:
If the plane was ‘under controlled flight conditions’ during all of its maneuvers and those were done with purpose to both mislead tracking (the north & south vectors) and to possibly incapacitate the passengers (the climb to high altitude after the drop to 20k...if that’s accurate), then it’s plausible that the last known vector was taken ‘as planned’.
Sri Lanka is well within the flight range of the 777-200ER and there are several airports I believe plausible for a landing/refueling scenario. If this was planned, Sri Lanka is the logical destination for a refueling stop (rampant corruption).
Perhaps the most logical, since most everyone is looking everywhere else for a plane that’s purported to have flown for up to a number of hours after its last radar contact...
Sri Lanka is a good guess. The shorter the trip, the better to avoid being noticed.