I cannot agree with that at all. I've spoken to people in revenue management and there was never a need to have a huge yield from J/F fares. They were merely the "icing on the cake".
You can operate a 747 or 777 across the pond just off cargo and WT Pax.
Sorry, ECC, but you are plain wrong. Without high yield (of course depending upon what you charge for flex fares down the back), the airline would operate at a loss, and I
have run the numbers personally.
I think your chum in rev mgmt might be looking too much at F/J redemption flights and too little at what the bankers were spending on the North Atlantic in recent times.