OP's primary argument is well established: demographics.
Sure, the decline in demographics is well established, but why does that lead to a crash? A decline sure, neutral or negative growth maybe, but a crash? Crashes usually happen due to catastrophic events (wars, bubbles popping, oh look our finance sector is built on a house of cards). I don't quite see from that article why this is a crash and burn situation, especially in places like Australia who have ready immigration to boost demographic trends.
Sure, the decline in demographics is well established, but why does that lead to a crash? A decline sure, neutral or negative growth maybe, but a crash? Crashes usually happen due to catastrophic events (wars, bubbles popping, oh look our finance sector is built on a house of cards). I don't quite see from that article why this is a crash and burn situation, especially in places like Australia who have ready immigration to boost demographic trends.