". . . but the dynamics of operating B747-200F's does not change the basic business model which is floored when oil is at nearly $140/Barrel"
Why would a business model be "floored" with the price of oil at $140/bbl...? Do you stop driving your automobile when the price of oil hits . . .$180/bbl? . . . $200/bbl? Do people stop living when the cost of food doubles? Any business model has to be cost based. In the airline industry, when "fuel costs" aren't passed on to the customers in a timely manner, then you run out of cash. It's elementary abacus logic.
The other observation is: Yes, that a 742F guzzles 13% more gas than a 744F. And the 744F in turn will guzzle more gas than the 772F. But the much more expensive 744Fs just aren't available to replace all 742Fs; and the 772Fs are still on the drawing board.
The cost of fuel is relative.