I think most agree the NRL should expand in the short term, with the main candidates being SE QLD-3 and Perth. I would say it is absolutely necessary for the long term health of the competition.
There are 2 ways to achieve this, relocation or adding 2 new teams.
I prefer to add 2 new teams. However, while there are 9 Sydney teams, the relocation idea will always hang over the NRL. Even at 18 teams, the debate will just move to how to include NZ-2, Adelaide, SEQLD-4...etc.
If I run a club, I'm conscious of this. If the NRL or ever turns the screws on a tight Sydney market (a return of the 'criteria', or even loosening the salary cap), I don't want to be the club to go.
A lot of people would point to the Roosters as one of the weak links, due to crowds or juniors. I'd say that no fans can be easily proven as a myth, and the club's investments in Central Coast juniors suggests active steps to counter the latter. Also that local juniors have little relevance in the viability of a professional sports team.
Another (un)popular one is the Sharks. I believe recent on-field success and more importantly their property developments have them in the clear for the foreseeable future.
It's worth noting that any of this can change in a very short period, and I'm not trying to attack any club here - boardrooms can rapidly shift, financial problems with them, and on-field form is the single biggest factor in Sydney crowds swinging.
But if the NRL were to look at a 'criteria' right now, 3 clubs stand out to me as vulnerable. I don't believe they should be forced to do anything but I hope their leaders are ensuring they have a strong position in the future should push come to shove in Sydney.
1) Wests Tigers.
Off-field form has hurt their crowds but 6k is an outlier - their average remains middle of the road for Sydney, if towards the lower end.
The bigger issue is the lack of a clear 'home'. The 4-4-4 home ground split spreads them too thin and I believe hurts fan engagement.
They need to decide what they represent and host the majority(I'd say 8) of their games at either Campbeltown or the new Parra (ANZ in the meantime is fair). Leichhardt's days of hosting first grade are limited and the region is not the Rugby League heartland it once was. If Campbeltown is not seen as adequate as a majority home ground then they need to find some other way to promote themselves and engage fans in the area.
Think of it this way - if you're gonna relocate someone, why not the mob who don't have a proper home to begin with?
2) Manly.
Management infighting is a recurring theme but the key for them is Brookvale. An antagonistic council charges them through the nose and long promised upgrades from various levels of government are yet to eventuate. With the 3 central stadiums getting major upgrade Brookvale only falls further behind the benchmark. Hopefully the Lottoland sponsorship results in the new stand getting over the line. Gosford has to be at least a back-up plan for Manly. Moving up the coast would give them immunity should the NRL ever decide it wants to push someone interstate.
3) St George.
Less so than the other 2 due to a stronger brand and more stable backroom but similar home ground problems to the Tigers which infuriates their existing fans and makes it difficult to get Wollongong fully engaged. The 3 way split is unsatisfying to everyone and the NRL loan still hangs over them.
Addressing these issues with a greater focus on Campbeltown, Gosford and Wollongong + other clubs taking games interstate or to the bush would take a lot of sting out of the 'too many Sydney teams' arguments and give clubs a stronger footing should the NRL try to force the issue. They're too conservative currently to try, but leadership and circumstance can change.
