For this week, I'm pretty sure Deans will put JOC (James O'Connor) onto the wing. Although Quade has kicked reasonably well, JOC (James O'Connor) will still be the preferred goal kicker as far as Deans is concerned. AAC (Adam Ashley-Cooper) will slot into 13. McCade stays at 12.
Obviously the loss of Ioane affects the defence in the 10 channel. I believe Deans will ask JOC (James O'Connor) too defend at 10. Deans will persevere with him for two reasons - on turn over ball the Wallabies now have the option to attack through JOC (James O'Connor) rather than Ioane just crashing it up (or Genia box kicking it or holding up the play to give Quade time to move up from 15).
Secondly, JOC (James O'Connor) is not a bad tackler and will be ok in the 10 channel. And JOC (James O'Connor) wants to be closer to the action also so he will be up for it.
Ioane is a massive loss as his work off the wing and combination with Quade is outstanding. The yards he makes on every run is brilliant for the teams go forward.
Horne won't be on the wing... and whilst heavily favoured by Deans, AAC (Adam Ashley-Cooper) will need a shocker against Ireland and Horne to be magnificent against USA and Russia to force his way in.
Mitchell will be on the bench and get maybe 30, 50 and 70 against Ireland, USA and Russia to build him up for the QF's. He may not even get this....
I can honestly see the backline for the knock out rounds shaping up as - Beale, JOC (James O'Connor), Horne at 13, McCabe at 12, AAC (Adam Ashley-Cooper) on wing with Quade and Genia. Bench cover from Burgess and Barnes on a 5/2 split. If 5/3 then maybe Mitchell/Ioane squeeze in.
Why no winger on bench perhaps? McCabe can always move to wing to bring on Barnes at 12.
Fainga'a sadly may lose his starting spot and bench spot now to Barnes due to versatility (10/12/15).
If Ioane makes it back so be it... like Horne, Mitchell, Barnes etc they are all an embarassment of riches for Australia in the backline at present.
Should Ioane be ruled out of the WC... I see potentially a specialist 7 coming into the side just as insurance. Assuming you can replace with any player.