The 767 is still the sweet spot for size, wingspan and utility. Like its sister 757, the '67 can make money on a 1:20 sector or a 9 hour sector. Yes, it has outdated technology, aerodynamics and structural weight. The current replacement aircraft are not the droids you are looking for however. Maybe the 787, but it seems to be more akin to the 330: ideal for a two sector day, not eight.
The closest aircraft to the 767/757 with modern technology that can handle multiple daily cycles and fit into standard domestic bays is the A321. QF have the ability to get plenty A321NEOs with their large JQ Airbus order, some of which are probably no longer required. Maybe we will see these replacing the 738s on MEL-SYD-BNE in the next few years.