I am no expert, but recently read about a cargo-door blow-out affecting a DC-10 (years ago). When the door blew out, the pressure differential between the cabin and the cargo hold caused the floor to fail, carrying away some seats with people strapped in....
If there is a sudden depressurisation in the flightdeck the pressure differential from the cabin would currently be relieved by the crummy door opening/breaking. If the door is stronger than Superman the whole bulkhead, or even the floor might go in the same circumstance.
Rather than needing a new door-lock an aircraft might suddenly lose hydralics, electrical systems, controls and/or the oxygen. Maybe the whole nose could detach like an Apollo command module, but maybe not...
