This will become a regular occurrence, with the 787-9 and A330-200 operating “mixed daily flights” according to Qantas. The 787-9 will also operate the morning QF119 service to Auckland starting tomorrow. These changes were supposed to be implemented in August, I guess they were brought forward.
It seems it won’t be too regular just yet. There’s only three LAX returns and three AKL returns in total with the 787 before it switches back to the A330.