Flog off Mascot and Canberra to residential, Port Botany, light industrial and Resort (e.g. marina and tower on the threshold of 34L) development
Build a proper, 24 hour airport somewhere Golbourn way with upgraded road/rail links not just to Canberra and Sydney but also the Illawarra coast.
Expand Williamtown.
The money to be got from flogging off prime real estate and developing the port would fund a fair slice of the new airport.
Problem with a second airport is who would want to use it. Richmond makes sense only as a secondary airport serving Blue Mountains and Western Sydney; like Avalon, a new market, but small. International freight volume is inexorably tied to the holds of passenger aircraft, and any attempt to segregate International freighters would be costly.
The "Japanese" solution was floated (
) years ago, but as it involved building taxyways over Botany Bay to runways which took out fish breeding backwaters, it was not well supported politically.
We will actually wind up with something that costs too much and delivers too little.