Had there not been the tax concessions, those property investors might've not invested in the first place, and thus, there would be an even lower baseline - the gov't's $20BN that they supposedly saved would not have made up for the shortfall either.

I rather the gov't give back the tax dollars in that case. And nothing stops an investor from making a company, and using that mechanism to negatively gear - unless somehow the proposal specifically targeted real estate.

People in australia complain about high property prices often think it's negative gearing causing it - but it's not. Australia is full of rich people, and high income earners. That's why property prices are high.