I know QF recently announced DFW - MEL flights starting in Q4 '22.
Do they have enough 789's right now to add that route?
Or is that new route predicated on QF getting more 789's delivered this year?
Boeing has three ready to go in Qantas colours that will be delivered by the end of the calendar year, possibly one with a special paint job
As above Qantas still has lots of cheap 787 options, and keeps its planes for longer than most (part driven by Aus tax laws), so the Boeing's will still be around into the late 2030s at least.
In terms of what's being replaced you've got to look at the age of the Qantas fleet.
1999-2005 20 717s NX*, YQ*
2002-2003 21 737s VX* (ex-AA post 9/11)
2002-2003 4 332s EBA-EBD (Dom only no IFE)
2003-2005 10 333s QP*
2004-2006 11 737s VY*
2008 5 737s VZA-VZE (last of the no IFE 737s)
2007-2008 4 332s EBG-EBL (Dom only no IFE)
So the new order of 20 220s and 20 321s is more a 1:1 swap of the earliest 717 and 737s. Possibly some of the younger 717s stay for a bit longer and 332s also get replaced.
Obviously more 321s will be ordered in future years for the remaining 737s.
But the next big fleet decision will be the 333 replacement.
I see this as either being 788s back from JQ (if the 321LR and XLR work for JQ) or additional 789s.