I agree with LongTimeInCX, the logistics of having to look after 239 pax and crew on some bush airstrip, with or without the heightened interest of the whole World watching, is just inconceivable. A friend has suggested that North Korea could, and might have, coped with such a problem, and certainly the aircraft had the fuel to reach there, assuming that all ATC units en route ignored a silent target and also that North Korea was expecting it - else they would have shot it down as it crossed the border - but there seems to be incontravertible evidence that it went the other way.
I think it is now undoubtedly at the bottom of the Deep Blue Sea - but where?
Location of the FDR will confirm how it got there, but only the CVR ( voice recorder ) will determine why, and if that is never found we might just as well consign the event to history right now and get on with Life.