For mine, with complete hindsight, the way to have done the NRL back in, say, 1980 would be to basically start a brand new competition above the then-NSWRFL & BRL/QRL comps.
I say this knowing such long-term future planning would have been nearly impossible given, at the time, the comps were locally based only.
Get a group of game-first,personal-alliegiances-aside type of people together. Form a national comp governing body. Then start a A-League / BBL type of location-based comp with the view to become national within 15 years. No 100yr old clubs with heaps of history and traditionalists who won't budge on their view of something that could be new and innovative.
New clubs.
In 1980, you'd logically have to start where League is the strongest: 2-3 in the larger Sydney area, 2-3 in the larger Brisbane area, 2-3 in NSW/ACT outside of Sydney, and 1-2 in non-Brisbane QLD. To be daring, with new big markets in mind, add in one from Melbourne. Perth and Auckland to come in within that 15yr period.
(I suggest the Melbournes, Perths, and Aucklands, as they were large-and-growing population areas where NSWRL Winfield Cup games were taken to in that same period of time in the 'real' world).
So by 1995, you'd have clubs based at:
* Sydney (southern, eastern & CBD area)
* Western Sydney / foot-of-the-mountains area
* Northern Sydney
* greater Brisbane area
* Northern Brisbane
* Southern Brisbane / Southern Qld (GC)
* Newcastle / CC
* Canberra
* Wollongong / south coast
* Townsville
* Cairns?
* Melbourne
That's a 12 team comp to start it off. Each area, bar Melbs, to use the existing local clubs / catchment areas as feeders.
By the early to mid 1990s, add in:
* Perth
* Auckland
14 teams now. Dots on the map. No 'x' area / city centric (which inevitably would happen whether NSWRL or QLD expanded into becoming the national league).
By early to mid 2000s, Adelaide, NZ2, PNG, ect, could all be practically vying to be added in. Maybe another regional Qld team, giving us full Australia and NZ coverage and a maximum of 18 teams.
Now, I'm fully aware that doing all this 41yrs ago removes the great tribalism League has, especially in the first several years, and it would have taken a LOT of money and radical thinking at the time (plus all the criticism that would accompany it all). But had this all happened, think of where we could be at now. For example, the Western Sydney team, encompassing the areas that currently have Penrith, Parramatta, Canterbury, Wests, ect, could quite possibly be getting 40-50,000 crowds, the other Sydney clubs 30-40,000 each, Brisbane 50,000 odd, strong NZ rivalry, 30,000 odd in Perth, Newcastle, Melbourne, Townsville, ect.
Local rivals, interstate rivalry, ect.
Had all this happened at the time, aussie rules would have been playing catchup and we may possibly be now in the much stronger position of the two. Union would be quite a ways further behind us too.
But anyway. It didn't happen. And given the nature of the game, the clubs, and the fans, it's pretty much too late to do this now.