I still say, makes no sense to "steal" the plane without knowing for sure you can't be tracked. How could they know for sure all the cell phones in the back were off? How did they know who had radar coverage and where? Impossible for criminal-minded to know all those countries abilities or status like that. One AWACS or P-3 in the area unknown to them could undo their whole plot.
How could you be sure someone at your intended destination wouldn't notice or report Maylasian T7 arriving/parked/refueled/departed? Surely they had to have all the details worked out and this only works if no one knows where they went. Impossible to iron all that out. One slip-up and their whole plan unravels.
Hard to say if Maylasian knows where/what happened, but all of the countries in that area with AD radar have reasons for a shoot-down, and a propensity to cover it up by keeping quiet. If they didn't shoot it down, they'd still keep quiet. I'd like to think negotiations are ongoing and a team is assembled to get to the aircraft and passengers, but that all seems just way too complex and too much drama for real life.
I agree that there will be a need to mandate/put a system onboard commercial acft for either passive or active pinging equipment. I would think a low wattage system could be installed that would be isolated from system, but able to relay info in regular intervals. Maybe initially only required for Oceanic flying or rtes with more than 100 miles of non-radar.