The loads on LHR-SYD are usually excellent especially since the 2x daily drop. Not a hope in hell they would drop it.
Trouble is it's not the load factor it's the yield that determines viability of a route.
The 'pointy bit' has never really been great on the Oz routes and due to the length of route it is hard to make the numbers add up.
I wonder what useage of the aircraft BA could make if it dropped the route.