I doubt pilot suicide. All the confusion for what?
All either pilot or first officer would have to do in order to commit suicide is incapacitate the other or wait until he stepped out for a pee, then lock himself in the cabin, pray to allah, and tip the nose of the plane sharply down. No need to shut off the transponder, that ACAR text messaging dealio, radio, and what else in order to cap himself.

If we're lucky their transponder failed and the Chinese overreacted and attacked and damaged the plane's cabin, letting it drift for hours until it crashed somewhere. No plane, no story, no apology.