Would you eventually get rid of Subbies altogether and just grow premier rugby? Maybe to a 2 division comp.
Not in those terms. I think I've said elsewhere we need Premier Rugby to serve a purpose - and it isn't "grassroots" as SRU would claim.
To me, Premier Rugby should be the prep school for pro players. It cannot, while it tries to be everything to everyone, in some cases actively working against other areas of rugby. Aspirational players should be in Premier, which needs to narrow its focus to prepping them for higher honours.
Take a certain number of Shute Shield clubs, and hive off their top ~30 players into the National Club Championship (NCC). Yes, this might only be 4-6 clubs from Sydney (and others from other cities), but set criteria and enforce them. In return they get funding from a streaming/TV rights deal to support the concept. Typically we'd end up with squads in the 19-25yo range, who are still young enough to take on the extra physical requirement for pro footy. However there will still be a few old stagers in there to teach them how to scrum, one painful lesson at a time
Those that remain form "Premier Division" in a competition right above Subbies First Div WITH the potential for promotion and relegation.
They align with Subbies Clubs across Divisions. This becomes a feeder or support system with 3 Grades + Colts max. The remaining Colts go play for a Subbies team or they spread talent to other "Premier Division" clubs.
Think of it this way:
Sydney Uni, Randwick, Easts, Eastwood, Marlins, and Gordon meet the criteria for the NCC and their best 30 players go off to do that. Some players from these or other clubs will also get picked up by other NCC franchises.
The remaining players at these clubs - basically 2nd grade down - are in the Premier Div for their local comp (Premier Subbies?) and align with local Subbies clubs right down the Divisions. They provide a bit of top-down support and in return the talent development load is spread out to other clubs and coaches.
The remaining clubs in what was Premier Rugby still get to field 3 Grades + Colts in "Premier Subbies", and also align with local Subbies clubs where available. It might end up more competitive as the powerhouse clubs have had their best and brightest moved to another echelon.
A club like Drummoyne might like to try and get promoted to Premier Div and take Two Blues' spot. Two Blues might then drop back to Div 1.
What you get here is a set number of grades, and therefore set resourcing every year, so you're not planning things on the fly.
The number of players that can filter back to Subbies Clubs, knowing they're still aligned with a chance at NCC, means there is still a relationship there.
And once you start bringing Junior Clubs into that alignment, and figuring out how best to work that in with schools, you're moving forward.
Rugby League do this, and they do it very well.