Lots of rumours floating around, another strong one is that any after this initial purchase will be "group" aircraft (well they are anyway if you think about it), and will be transferred between entities as required, as per the right aircraft right route, right airline mantra that group management seem to be so in love with at the moment. The same rumour is floating around for the short haul fleet with commonality between Jetstar and mainline, or whoever flies them domestically for Qantas (Qantas link)...but that's another thread.
We all love our rumours and seem to hang on to them for hope, but the truth is when there is a fleet of 787's sitting on the ramp with a big roo on the tail being flown by mainline pilots is when I will start celebrating!