Most of the speculation about this peaked quite sometime back. As mentioned QF and CX haven't wanted to play together for some time. Some carriers being excluded from certain fares isn't unusual or new.

Also see the discussion in these threads:
http://www.flyertalk.com/forum/onewo...ght=qf+leaving
http://www.flyertalk.com/forum/qanta...ght=qf+leaving
http://www.flyertalk.com/forum/briti...ght=qf+leaving