And then - if the codeshares DO happen - the matter of how to treat priority passengers.

Priority baggage, check-in, lounge access.

Although, this could also work in QF's favour. Someone flying on a cheap UA fare from (say) PER to SYD to LAX and return, after experiencing QF on the Australian domestic flight and then UA on the trans-pac, might elect to fly QF next time - particularly if flying in J or F.

Dave