When comparing 2 744s to 2 772s + 1 787, the seat breakdown is:

128F+J/140Y+/480Y- vs. 136J/214Y+/403Y-

Except for 3 seats, everything UA loses in Y- they make up in Y+. They also add 8 seats overall to the 'premium' category, but lose F entirely, and the revenue from those who'll pay the higher J fares to upgrade. There's also the cost of running those 3 planes vs. the 2 747s (don't know if that's higher or lower overall).

I think returning a nonstop to MEL is appealing, which is why I asked about the 787 scenario earlier in the thread. One of the questions is how many people continue on to MEL, and if it isn't a 787's worth, can they capture some of what the other airlines carry, considering QF has an A380 flying LAX-MEL.