I have a different take on this; I don't see the point in having any specific FA/pax ratio. IMHO if the number of FA's is tied to safety, the number of FA's should be tied to the number of emergency exits that must be manned in an evacuation.

Take an A320 for example, there are 2 forward exits, 4 overwing exits, and 2 rear exits. In the event of an emergency, it is pax that operate the overwing exits; FA's are likely not a factor for these exits. The 2 front doors and 2 rear doors would likely be manned by FA's; the question becomes is one FA required per set of doors, or does each door require an FA? I assume that since on a small plane such as a CRJ only 1 FA is required for the 2 front doors (based on the current ratio of 1:50), that only 1 FA would be required for each set of doors on a 320. Using this method, an airline could probably justify going with only 2 FA's, and possibly having a 3rd for giving commands over the PA.

Note: I am not advocating for only 2 FA's on an A320 (based on AC's current config of 146 seats that would be 1:73), I'm just saying that don't necessarily agree with the whole FAax ratio argument. Also, from a customer service perspective that ratio would be terrible.

If the argument were that each "door" needed to be manned, then on the A320 4 FA's would be needed and going from a 1:40 to a 1:50 ratio would not accomodate that.