The media are clueless, apparently so are Malaysian authorities, so here’s my take:
Malaysian flight 370 was taken by team aligned with Islamist ideology.
The plane was taken for use in a future event.
The Malaysian authorities are: a.) embarrassed by their own security ineptitude, b.) desperate to avoid the appearance of that ineptitude, and c.) unwilling to admit their nation is not compromised entirely of the secular melting pot they espouse to the outside world. Indeed Malaysia has been yet another nation with internal Islamist conflict despite their diligent efforts to obfuscate in that regard.
To that end modern Western nations, and their more sophisticated intelligence apparatus, are growing increasingly frustrated with the refusals of the Malaysian authorities to admit the obvious. The flight was taken, perhaps by Malaysian nationals, with an intent yet undetermined.
A serious amount of planning and logistics would have been needed to pull this off. Also, a great deal of skill and simultaneous luck would have to align to “disappear” a Boeing 777.
The “takers” would have been aided by surprise and the unexpected. In the middle of the night a shadow flight is entirely possible through all of the regions being discussed as possible routes.
The radar capabilities in the Western China region, the ‘stans’ and the mountainous areas of the Northern Middle East are generally archaic, not staffed, and only activated when there is a reason to be looking for something. A surprise flight with no advanced notification could easily slip through undetected almost to anywhere.
Why would a terror group not claim the event? Quite simply because they have no desire to outline their intents or draw attention toward themselves. If they plan to do something with this plane why would they announce they have it.
As a consequence it’s reasonable to assume all the passengers were viewed as immaterial to the event itself. The goal was not hostage taking and any passenger surfacing would be viewed as a risk to the mission itself being discovered. So they were most likely killed during the event. Perhaps while still seated, during a planned decompression and strategic oxygen loss event.
Where is the plane? It could be in any number of places – concealed, covered, and now available for the next stage of its usefulness.
Who is the intended target ? Whoever is viewed as the bigger infidel !!