Australia's problem for many years is that they had players who considered themselves bigger than the team, it was a serious issue and part of the reason Robbie Deans couldn't get the results he should have. They had players who could call the CEO anytime they disagreed with the coach and who required special attention. It wasn't really resolved until Michael Chieka came in, on the condition he had final say over the players and their roles in the team. Say what you want about the guy, but he completely turned the team culture around. The issue now, in my opinion, isn't the team or the players, but the management and unless the coach who takes over can get a better relationship with management and resolve a few other key issues, I don't see results going their way regardless of who's coaching. I see MC's main fault being he was very good as a players coach, and perhaps a big-picture guy, but not particularly good as a details guy and a horrible horrible selector (too prone to allowing his feelings to dictate above all else). I feel it's correct what he said about not really studying his opposition and insisting on one style of play with complete disregard to the other team. External Selector was a great step for Australian Rugby, as it was for NZ too in it's time (Something I hope they will continue with post-Hansen). I feel Joseph and Brown would resolve those key areas, but the one thing I really don't think would work is Kiwi's coaching Australians.
Castle and Co need to go, for Australian Rugby to move forward really successfully, and success under a new coach would be in spite of them, not because of it. Rod Kafer is someone I feel has the understanding of what's required.
Coaches for NZ, I personally think Foster should be given the role, but I wouldn't be too upset if it went to Joseph and or Robertson (though I suspect there is a risk given he hasn't done any international coaching really). If Foster wasn't given head coach, I believe it would be a mistake to discard him, so I wonder about a director of Rugby role, so we don't lose all that IP. If Foster isn't retained in some significant capacity, I think he'd feel justifiably poorly treated, and if you take into account the players we are losing, then Hansen Foster, Cron, Smith (who went a while ago), Tew, and possibly Enoka and Shand, we are pretty much tossing out the last 15 years of knowledge gained.
Some might say that starting completely afresh is a good thing, but I believe it would result in a pretty mixed bag for NZR for the next 2-3 Years.