I think cockpit visits will be possible no more due to this
terrible attack. In the U.S. it wasn't possible before to visit the flightdeck during flight, on the ground it was.
In other countries it wasn't prohibited to visit the cockpit during flight, depending on the flightcrew's decision.
All this will belong to history right now, I think you will be even a "suspicious" person when you ask the flight attendant for y a quick look into the cockpit!
What do you think?