Actually, I was interested to learn that Wino's 757 freighters already have isolated cockpits. The company I work for have about 48 747-400s with about 8 freighters & we fly them all as 1 type. The freighter cockpits aren't isolated from the rest of the airplane; we have total access to the main deck, although we don't have any procedures that require us there in flight. The only parts of the airplane we can't get to are the lower cargo holds. But that's an interesting thought all the same, but I'm personally not keen on being completely cut off from the rest of the aircraft.