Wiz I'm guessing it's all about the premium seats, as well as offering a superior product in Y to the Qatar product which is better than the 200LR offering in our birds.
As for payload, they are going to have to block about 100 seats or so in Y to make it work as well as sending all the freight via Oz just like they've been doing, or tacking on a 77F sector from SYD etc.
I've done the trip twice, it's a killer, but I did have 3 very happy colleagues able to go home and visit family.
Sky cargo will hate it, but the pax will love it, and if it won't make money or at least break even, EK wouldn't do it.