The problem is, and I believe always has been, that the people in charge of rugby league (and rugby union, soccer and AFL for that matter) have tunnel vision and will only think of expansion in terms of stealing supporters from rival codes.
The one thing that the RUWC has shown us is that people from all codes can enjoy the spectacle of international football. Until all the major players, the boards of the rival codes and the media, get together and start putting their collective grey matter to bring crowds into stadia, you'll only see a continuation of the past. That is one code has a push for greater market share to eke out a marginal improvement at the expense of the other footballing codes, gradually tapering out as the other codes do likewise.
This could be accomplished at a team level and need not be necessarily limited to footballing codes. Newcastle forging links with their soccer and basketball teams. Members of the other clubs receive heavily discounted admission into matches, scheduling is done to tie in with each other, not compete against each other, and so on and so forth. In Canberra, this could be achieved with say the Brumbies, Raiders and Capitals. Not everyone is going to take up the offers, but it should ensure that stadium crowds are bolstered for all teams and helps all sport to grow.