Melbourne was full of airports ontop of those already mentioned. Many aircraft were built & test flown there during WW2.
Laverton has gone, "Mumbai Cook" still there but down-sized, Essendon tapping along nicely with plenty of work while Avalon is looking bright: Libs (Sarah Henderson) have pushed through approval for an International Terminal at Avalon, additional to what's already there, plus a train station. The train/rail connection is a winner not only for pax but for freight & fresh produce, given it also sits on the "National Guage" line as well. Expect more hire car services etc their too. There is good interest from International pax & freight ops already.
Pity Melbourne's recently completed International Terminal expansion is already grid locked at certain times of the day, as demand is definitely there.