Melbourne will become the economy hub of australia, with all the business going there instead of sydney. Melbourne grows by about 100,000 a year, in a few more years experts say it might be 120,000 (10,000 a month) sydney has a height limit of 275m, so it can't catch up to melbourne. Melbourne also has a 298m building currently under construction and over 50 projects over 150m.
So, melbourne will surpass sydney in almost everything.
in 2050 the population of the cities will be:
Melbourne - close to 8 million
Sydney - 7.6 million
Brisbane - close to 5 million
Perth - 4.2 million
Adelaide - 1.8 million
some sketches of Melbourne in the future
i think the last one is quite funny