My personal view (history will decide how accurate my view is):
Most of the 18 A321LR's will go to JQ to replace the B787-8 on Bali services. The remainder will probably do mainline routes that require more capacity than the B737-800's (QF domestic badly need an aircraft between the B738 & A332, ie they miss the B767) - who will fly them will be the major industrial firefight as QF has been grooming Network to fly single aisle Airbuses at a lower rate than mainline.
The massive order for A321XLR's will probably all go to JQ to replace B787-8's on Asian & Orient routes with the later deliveries operating to Bali thus freeing up the LR's to be transferred to mainline domestic routes (just in time for QF to pay for the first heavy maintenance check).
All the JQ B787-8's will be transferred to mainline to replace the older A330-200's on Asian routes - the oldest A332's are near the end of their life and no replacement has been announced (or even a project started to look for a replacement so it looks very likely that the JQ B788's will fill this role). The big problem for QF management is that the B787 award is heavily biased towards pilot savings on the LR & ULR routes but they are more expensive than A330 pilots on Asian routes - I suspect that this is where Tino the Spiv wants savings in the QF B787 award as announced in his nasty email.
The only JQ Intl route that the A321XLR's won't be able to replace the B788's on is HNL but, as the market has been saying for a long time, pax don't want to be dipping into their wallet on 9 hour sectors and thus prefer a premium product. Hawaiian blew JQ away on the BNE-HNL route due to better product & pricing). Thus, I believe that mainline will operate the route with a daily service, no JQ services.
This adjustment to fleets would leave JQ with effectively a single fleet (wrt pilot endorsements) and relieve it of the cost burden of running a relatively small fleet of B788's. It's been apparent for a long time that the B787 family (-8, -9 & -10) are perfectly suited to replace the A332's & A333's in mainline so the JQ aircraft are perfect to start this process. This is the first time in Napoleon's tenure as QF Group CEO that there is a bit of logic in fleet planning/strategy - he's made a lot of stuff-ups in the past.
I know that there will be some who disagree but I think this plan is logical and relatively free of bias.