German wings case is a rare occurrence and I don't think it's avoidable with two in front.
There is a reason its a rare event (although its not an isolated event), because you do have two in front. In the pilot suicide examples. Germanwings, Silk Air, Egypt Air and MH370, the two pilots have had to become single pilot in the cockpit for the suicide to happen. All Airbus are doing is creating exactly the environment that a pilot with mental health problems requires to end their anguish.