The FIRB hands are tied since Joe Hockey introduced the $300 AUD floor for Foreign ownership provided that it doesn't threaten National Security.* He was asked in China when he announced the floor " What if the sale is just marginally above $300 mil and his answer to the Chinese Media was "just see me".
IMO there should be a caveat on farm land to the extent that the sale to foreigners can only be leasehold with a max of 30 years. This will give locals a fighting chance and could serve as a precedent to future mines' sales, IMO.
*The Chinese offer to buy the Kidman properties was knocked back because one of the holdings adjoined the Woomera Test Site.