Very interesting thread ... thanks to Goldie for sharing your in-depth knowledge and giving us your slant on all the scenarios suggested.
My musings just now were ...
It seems to be said that if the plane went along the 'northern corridor' route there is the slim possibility it has somehow landed, although very unlikely.
If I follow correctly, it is thought that if it went along the 'southern corridor' route it for 7 hours it most likely ran out of fuel and crashed into the sea.
My question is: Are there any land-masses big (and flat) enough, like on an uninhabited island for example, where a runway could surreptitiously be built? I mean along this 'southern corridor', or is it just a vast expanse of ocean?