Jacpbs Well Airport
My understanding is that the old DCA used to have quite a bit of land in the JCW area (Commonwealth or Crown land) which was originally set aside for possible use as a future airport. This land was acquired just after WW2 but following the redevelopment of Brisbane Airport in the 1980's this never went ahead.
I'm not sure of the current status of the land there now, given the infrastructure money that's poured into Brisbane by the industry and present owner over the last 15 years, it is difficut to imagine it being shut down, and Coolangatta's passenger numbers are climbing although its GA activity is a shadow of what it was in the'70s.