It's odd to say league hasn't transitioned into the professional, commercial era when the entire split between league and union before WWI was based on league players being paid while union stayed firmly amateur - until 1995 anyway, when too many were being siphoned off by league. But yes, obviously since the eighties there has been a new, national, commercial era, and league's transition was very obviously not smooth.
I do wonder if there is enough room in this country for four football codes. I think union is the code that will become marginal though. Union, once it went professional, made the transition better than league in other countries, no doubt helped by it being a more international sport in the first place. But in Australia it's always been second fiddle to league, and if the depth stops coming through, well, Australian interest in the sport is very much based on the Wallabies being successful. Soccer is making big inroads that probably threaten union the most, and the AFL has been most successful at becoming a national competition. Plus Aussie Rules has a history of being more inclusive than any other code; the participation of minorities and the sizeable female following put all the other codes in the shade, and that will obviously help it grow.
Will be interesting to see what the future holds.