If negative gearing is abolished then the gov't would have to provide the housing that at present generates $13.2b in losses, of which, the gov't gives tax refunds of $3.96b while private investors out of their own pockets provide $9.24b. It would cost the gov't $13.2b and not just $3.96bn.
Those renters should be thankful that they are paying lower rents subsidised by private investors otherwise they'll have no accomodation unless the gov't provides more housing.
Perhaps, rents should be raised to cover the costs of holding those properties then there would be no $13.2b losses.