It doesn't make commercial sense to send a 747 load of passengers to BKK, HKG or SIN from either OZ or the UK in the hope that a BA or QF 747 will be there waiting to take them on to their destination. There are too many variables to be able to deliver that consistently.
What does make commercial sense is to persuade the regulators to allow cabin crew and pilots to operate each others jets, if that can actually be done. (Big unanswered questions there.)
The other possbility is that BA and QF form a greenfields co-branded worldwide airline with the 787's on order (139 of them over both airlines). In which case they will try to keep BALPA and AIPA out of it, or play one off against the other.