I think Liberty's point above was the right one on these announcements. This tax does not need to be effective it just needs to change the psychology.
Housing bubbles need 2 things, cheap/easy to access credit and psychology (typically due to some narrative, houses only go up, supply, foreigners etc.).
Credit is being restricted by the big 6, everyone I talk to it's harder to get a mortgage from them. The next providers were the HCG's/EQB's of the world that sourced from the Broker network. HCG announcement should mean that credit availability will be much more scrutinized and brokers more wary to cheat. So credit is availability is shrinking quickly.
The last thing is the psychology, this seems to be cracking (just from hearing what the average person is saying, newspaper headlines, comment sections etc), so if a new tax can kill the narrative for the last buyers this thing ends soon.
My view and portfolio position is that this is over.