Is the point of the excercise that they will make ADSC subscription compulsory in the relevant airspaces?
No the point of this perticular trial is to assess the load on the ATC system if the interrogation rate is increased to every 15 min instead of 20-30.
Nothing to do with MH370, and , as said previously , it would not have changed anything if the rate had been 15 min at the time.