Chill
What about if it came down somewhere central on the Malaysian peninsula? Picking out bits from what's been reported to go from the original search area (last known contact driven) to the west side of the coast implies it was turning back and would cross back over the land. The MSAs are pretty high in the area up to 9000ft, if it went down in the mountainous areas it could be difficult to locate, especially under a canopy of trees (although I'm not familiar with the terrain details of that area). Maybe the crew were doing their best to manage a catastrophic issue caused by whatever event. However I cannot fathom why the ELT has not been detected unless it was an instant catastrophic event that disabled it but then that would put it closer to the area of last known contact. Unless it was a high G impact of course. However I would have thought ATC/military would clearly track the aircraft if it changed course, surely it would look out of place on radar even if it was trying to make land fall somewhere?