As an Australian who has paid close attention to these matters for many years, I share your concern but think the assessment is overblown.
The housing boom is driven by a combination of: (a) Australia's cultural devotion to home ownership as a conventional life milestone; (b) foreign investment and immigration, and (c) high incomes due to the mining boom and prolonged overall economic strength. Of those factors, (a) and (b) are not going to end any time soon. A global recession/economic crisis would obviously affect (c), but Australia has weathered several of these in past decades. If/when it happens, it should cause a slowing and/or a correction, but not a total crash, unless the world economy crashes. On the other hand, continued global growth, particularly in China and India, will keep fuelling demand for Australia's resources, products, services and land. Why is the worst-case scenario more likely than the best?
The political situation might seem grim, but it's not nearly as bad as the US or the UK or parts of continental Europe.
The "brain drain" issue has been a concern for many years, but if anything I'm starting to see that reversing; people I know who had left for Silicon Valley or New York or London for better career opportunities are now looking to move back, because Australia seems so idyllic compared to the chaos that's reigning elsewhere. I've noticed a vast improvement in the scale and quality of entrepreneurial activity in Australia in the past few years, and I keep hearing from expats that they're noticing how much better things are getting back home, and how much they'd like to come back and be a part of it.
The NBN is an issue that people love to use to hurl abuse at the government whilst simultaneously complaining about ballooning national debt. You can't have it both ways. It was a costly and risky project from the moment it was conceived by the previous government, and since then it's just been a case of getting it done while keeping cost blowouts and delays to a minimum. As a technology professional who cares about fast broadband as much as anyone, I can tell you that the NBN services I've had at my previous home (FTTB) and my new home (FTTP) are as reliable and fast as I could hope for, and I find cellular and terrestrial internet in Australia to be at least as good, and usually better than what I've experienced on recent trips to the US.
I don't deny there's cause for concern; I've been as mindful of, and worried about the risks as anyone. But painting it as all negative, and pinning all the blame for all the problems on the current government is inaccurate, unfair and excessively pessimistic.
So yes, there are challenges; there are great challenges everywhere in the world, as there always are. But there are also great opportunities and reasons for optimism.
It pays to take a balanced view.