I know this is discussed up thread but I struggle to see what this is going to solve. On Golden triangle routes up to half the plane or more can be "priority". Likewise there's been studies heck even a mythbusters episode about boarding a plane which proved zones are slower but increase satisfaction.
Using American Airlines and the 8-9 zone system they have in place, they divide the entire economy cabin including on wide bodies into 2 zones (towards the end) and the majority of the zones are status (1-6) which is nothing to do with boarding speed but more customer satisfaction.
Qantas is dividing the economy cabin into 4 zones but will lumping everyone with status change much?
At the end of the day if they want less delays then don't schedule 55 min turns in cities like Sydney or Melbourne which seem to change runway or operations every 20 seconds. The published arrival/departure times are meant to be the wheels up/down time, this means in the 55 minutes from when the plane hits the runway it's got to taxi (can easily be 10 mins in SYD), connect bridge/stairs, boot self loading cargo off, sometime re-cater, pretend to clean, load new self loading freight and then taxi back out for takeoff.