It's all about competitive tension.
If 7 breaks 9's first and last rights monopoly, 9 will be effectively forced to bid blindly. Meanwhile it opens the gate for 7 & 10 to henpeck which elements they wish to compete for. Also all timeslots are open for direct bidding by Fox but it can work the other way, with the NRL group F2A packages for Fox's existing monopoly and then using it as leverage to increase Fox's deal. Then you also bring changes to structure - offer things like Sunday headers and increase running lengths, for instance have a 1:30pm to 6:00pm NRL block on a Sunday.
The more complex the variables, the more blind the networks are to each other's bid, the higher the deal.
It's really hard to put numbers on these things because there are so many variables involved. I did comment in another post though that by doing some of the things I've mentioned previously (Friday simulcasting, Sunday double headers, 2 Brisbane teams on F2A a week, having a combination of fixed/floating scheduling, perhaps extending the season by two weeks with 2 byes to create 2 more weeks of F2A matches) that our advertising revenue from F2A along could start to pull upwards of $90 million a year - not including the Halo. In fact, I believe that I may even be a little bit conservative in that. However that won't be the opening bid. The opening bid from 9 will be for the existing package and what they roughly consider to be their direct break even. After that the NRL can throw a variety of options at the networks.
If we can get real competitive tension across all platforms we can see some big increases. I have heard that one of the 12 shortlisted commissioners is a very well known media buyer and he's an expert at these negotiations. Plus LEK strategy are involved.