Your review can be summarized in short: Waggons have not been updated since 40 years. Maybe they should update their waggons. Oh, they axed that plan. Again. See you here next year. And the year after.
Personally, I don’t think upgrading locomotive-hauled stock is worth investing that money into anymore. They absolutely should have a decade ago, but trying to do that now to delay an inevitable upgrade to a more efficient D/EMU design seems like a waste of money.
What I’m more frustrated about is the missed opportunity here for state cooperation. If the government’s of Qld, NSW, Vic & SA (with federal funding support) all collaborated on a long-distance train-set, then it would benefit a lot more people for a lot less money. You could replace the useless Overland service from Melbourne-Adelaide, and bring public services back to routes like Sydney-Adelaide (currently $795+ on the Indian-Pacific). It could be built with gauge-changing bogies so state regional train authorities can use it too.
But there just doesn’t seem to be any political will for that on a federal level, and the state’s certainly aren’t going to suddenly cooperate on rail standards after 150yrs of bickering.