Super Rugby would be a better tournament for more rivalries, better engagement and better marketing. It lacks severly in those departments
IMO NZ could've sustained 14 Super Rugby teams by this point, if it had realized the tribalism associated with the NPC, was not worth trading in, to be part of a glorified All Blacks trial run of a tournament. The 14 provincial teams, could've doubled as marketable brands as well on top of the historical connections. E.g. Auckland Blues. Southland Stags, North Harbour Pirates etc
The Australians whom start out with significantly less fanbase and resources per capita to often deal with the NZ sides in terms of quality would finally have a product where they are likely on an even footing. NZRU can't afford to run both the NPC and Super Rugby, that much is obvious in so far as the All Blacks brand is the top of an upside-down pyramid. NZRU to save money would logically prioritize one of these tournaments, so to prevent the current bloatedness of most NZ consumers feeling as if there are too many games a year to attend or to keep up. Centralizing the interest in a given tournament so to speak.
The Ranfurly Shield must stay in this hypothethical however, as it has immense history. Keep it between just the NZ teams however.
You could have 3 "grand finals" in one tournament". An All Aussie final, An All NZ final and the Overall final. Using the ladder positions at the end of a round robin would determine the finalists for the domestic finals. With Quarters and Semis for the Overall. Everyone plays everyone once. Simple
All Blacks would be finally playing for their province on a regular basis, as they have the oppourtunity in a world where these games don't clash with the Rugby Championship. Australia would have 4 teams, NZ 14 plus the Drua and Pasifika whom would probably win games in this edition. The Quarters makes sense. It's 8/20. There are 10 games a week for broadcasters. Which means a lot more afternoon footy. Ticket prices would be slashed, jerseys announced all on the same day across every team. Sure, there are flaws, but at least this idea sees imbalance of quality, lack of genuine historical rivalry and tries to fix it, instead of plonking random teams across the globe.
In conclusion, Super Rugby will ignore any logic, run the tournament into the ground through predictability of outcome, lack of meaning and stupid decision making. The fantasies of what Super 18 couldve been will be ringing in their ears, as they chase money grab one off teams in the US and wherever hosts a world cup going forward. Does it make sense?. No. Does it make the people running the tournament loaded, Definitely.