Because they overpaid for the AFL and got out before the shit hits the fan. The AFL deal isn't sustainable without a sweetheart NRL deal.
That is very likely true, Once they have a date for HBO going the value drops further
I see it as they keep both or neither, If they want to continue to produce content. Then they need the big 3 they have already.
Should they want to go down the Path Amazon and now Netflix have shown as taking feeds from elsewhere.
Then adding F1, Supercars and so on that rates decent enough but looks a better fit and saving $600m along the way.
Atleast there is 3 years of the rights to go. Gives them time to acess