@Verminski
There is no reason that I can think of that you wouldn't implement a Northern Australia Development policy and plan simultaneously with a plan to repopulate south east Australia with breakthrough, enabling transport infrastructure like one of the competing very fast train systems already available.
An understandable point of view from many in this thread is that Australia cannot or should not pursue a deliberate policy of growth by immigration because of say lifestyle/environmental/sustainability issues.
A few others point to what is essentially chronic under population by global standards, particularly by near neighbour standards, and to the risks that represents.
The world appears to be in a state of flux and possibly entering a period of heightened power tensions ... with possible long term outcomes that can barely be comprehended at present.
The current discontent in Europe for example is possibly a golden opportunity for Australia to cherry pick immigration skills to suit our future needs. To target demographics and skills of our choosing if you like.
To employ these people there has to be abundant opportunity, the likes of which can be created with formalised Northern Development and formalised plans to repopulate south east Australia with themed, vibrant, energy and services efficient, connected regional cities. These same new cities and ongoing regional development they will facilitate take the pressure of Melbourne, Sydney and Brisbane and reduce the adverse affects of erstwhile evolving super cities.
Australia supporting a vibrant, thriving 40 million population of targeted demographics and skills is likely to be more stable, sustainable and dare I say more defensible than the current trajectory might suggest imo.
Dex