I was recently on an EasyJet flight and was chatting with the FO during the cruise about flying Microlights and other aviation fun. When he went back to the flight deck, I noticed that the Captain had been left in there alone.
I asked the cabin crew manager about it and she explained that the 2 person cockpit rule was abolished some time ago (she couldn't remember when) and that the door is now opened via facial recognition (I did notice the FO look up at a camera to unlock the cockpit door).
I then asked her if the door could still be locked from the inside - she confirmed it can.
So my question is - how does this prevent another Germanwings? I asked her this question and she agreed that really... it doesn't.