The answer to freeing up more housing spots is not booting 'undeserving' people (that in itself is subjective). We need to address why rent is so high i.e buying is becoming unobtainable now, so there is huge demand for rental and landlords see dollar signs.
Personally I would like to see a formula for rent, like a ceiling price, monitored by a body. Based on the suburb, number of bedrooms, size of yard etc etc. LL's then couldn't charge obscene prices. I also think the first home owners should be increased to make buying easier.
These measures would help to ensure people could afford and get access to private rental and move on from public housing so others can take their place.