I'm more inclined to believe that it landed somewhere and is being repurposed for a terrorist attack. It still seems too strange that no credible debris was ever found.
I am not suggesting you are wrong, but as a point of reference, we are looking for at best a KM of debris in a possible 5,300 KM radius, resulting in a search area of 88.2 MILLION KM. So your chances of finding something is 1/88.2 million or a 0.0000000114 chance of actually seeing debris.
I am going with Occam's Razor on this one -- the plane crashed in a hitherto undiscovered place.