A 777 300ER burns 8t an hour vs the 744's 10t an hour. Carries 400 to 440 pax, same as a 744.
J* have a swag of ex 777 drivers from SQ and a couple from EK, so they can certainly crew them. Plus J8 drivers are cheaper than QF mainline ones.
Dunno, but I reckon J* could see the 777. Soon.