EDIT: not only rental apartments of course but more housing in general.
A second step would be, to make sure that rental housing is used for that instead of AirBNB or any other investment. It would also help to reduce land transfer tax if someone then lives in the bought flat. Speculators and builders anyway get around it in the long term by founding businesses that buy apartment blocks (pay the tax once) and then later only trade the shares of these businesses.
And last but not least, they should stop to discuss dispossessing property. It does not solve anything but wastes time and energy.