Prior to COVID, the plan was to replace the A380 on the Dallas route, in 2021, with a QF B787-9 SYD-DFW-SYD and an AA B787-9 DFW-BNE-DFW which would have resulted in more seats able to be occupied out of DFW and lower costs despite there being two aircraft and crews invovled. If, against all predictions, some of the QF A380's are brought back into service some time in the future, it would be very unlikely that they would be going back to DFW.
AA would have preferred that QF operate both flights but the US Government required AA to do their share of flying that occurs under the JSA so they elected to operate the service to BNE.