I agree with most of it mate, but if I coached the ABs I would want the Aus teams to be weaker as it gives my players less high tensity matches surely, that was only question I has in asking how Aus having less teams would help ABs. And how is a 5 team comp in NZ unsustainable (I agree) and yet a 5 team comp in Aus is?
Think Andy Marinos actually had a few good points when he said he felt Super lost his way, said that Super was always set up by the 3 countries as an elite comp to set up players for international comps, not as a domestic comp, while not agreeing with all his thoughts it is what I always thought it was too. Then they allowed to get diluted by letting countries add teams that should of been in a domestic comp.
What you describe in retrospect not allowing additional teams into Super would simply have seen the same trend, just steeper. Here in Australia. It may have kept the quality up but eventually at great cost.
You are right of course - 5 Teams in Australia, on it's own, is no more sustainable here than it is in NZ. But in a building phase it is fine in the interim. With Covid it is a great time to reset the whole professional game here. And far far superior to two or three teams in a. AB Development comp.
Neither do I think a TT option with NZ and Aus with 5 each is sustainable. It will die more slowly but is not likely to prove tenable. If they spread NZ to 8 teams as mooted an 8+5 could work.
A champions league at the end of a domestic comp can work. I'd prefer the the Aus teams to be representative, but that's just me and has not met with support here at G&GR.
The reality right now is that any TT based on what NZ are looking for is not tenable for Australia. IMO. Australia needs to sort it's shit out through a largely domestic based comp or at the minimim, an evenly based comp (roughly) that could involve :
a) more active NZ support - increasing teams or spreading talent to Aus
b) other teams eg Japan, PI, Argentina etc
But it needs time to settle as a commercial product here in Aus. It is a much more competitive sporting environment here. It is also a much larger commercial pie, and only a few percentage points in fan support taken from (or shared with) AFL/NRL/Cricket could make a huge difference.
Thence reconsider the TT. If NZ don't want us at that stage we still have a successful comp. The options are both a win.