If true this would be very suprising, because:
1) With 3 daily services there are simply not enough B744ER's (pax) in existance to cover them. There are only 6, and each daily Oz-UK service requires 3 aircraft, so thats 9 aircraft now and 12 next year if 4 daily goes ahead. (Which seems likely, but who knows?)
2) The ER
's were purchased specifically for MEL
services which have longer sector lenghts than Oz-UK and hence utilise the greater weights available with these aircraft. While they have shown up in LHR
) (FRA / FRF / EDDF), Germany">FRA?) before it has not been often and generally has been for one off scheduling reasons. A wholesale shift to the Kangaroo route seems unlikely.
You might see more of them during your summer as the head winds across the Pacific die down a bit during the northern summer, making the extra weight not quite as critical then, as compared to the rest of the year.
Any more info would be appreciated.