I didnt think the FFA had control over expansion either, but an extract from the link states:
"The regulatory functions of Football Australia also include a new club licensing framework for the Professional Leagues and control over access to the Professional Leagues (whether by expansion, contraction, or promotion/relegation), the AFC Champions League, FFA Cup and all other domestic and international competitions."
Football Australia and the newly formed Australian Professional Leagues (APL) today announced that terms have been agreed to ‘unbundle’ the A-League, Westfield W-League and Y-League (‘Professional Leagues’) from Football Australia. This unbundling of the Professional Leagues from Football...
www.footballaustralia.com.au
I hope the pizza does get bigger too, but after many years of promoting our code, football crowds seem to be dropping, [not increasing] and the competition from other sports doesn't suggest that such growth is certain. More areas represented doesn't necessarily result in greater interest, or more fans- eg Gold Coast and NQ Fury.
I'm keen for expansion in the areas you indicate too, but I also think relegation and promotion is necessary to prevent any repetition of low spending perennial wooden spooning.
I love your optimism, and only wish you could influence the FFA and APL into the direction you suggest.