I never thought about it, but these regional teams actually made it harder to clear out Sydney via relocation
The biggest cities/regions within the borders of NSW (following Sydney) are:
Newcastle
Canberra
Wollongong/Illawarra
Gosford/CC
If we had left these vacant, we might have seen NSWRL clubs voluntarily move out of Sydney (We saw Bears try to move to Gosford, Jets try to move to Campbeltown, Magpies actually move to Campbeltown, Dragons basically absorb the Illawarra)
Maybe moves to regional NSW would not have felt as dramatic as moves to other states.
That's an interesting "what if". On the positive side, you preserve all the classic NSWRL brands from circa 1980, however as far as competition size goes, the gains turn out to be minimal, compared to what we currently have via mergers.
If instead of expanding to Canberra and Woolongong, the league decided to relocate St George to the Illawarra and (let's say) Newtown to Canberra, you have 12 teams with a bigger geographical spread. I picked Newtown as going to Canberra as they were struggling financially, so maybe they the league nudges them towards the ACT instead of their choice of Campbelltown.
The next club to hit the wall is Wests, so maybe the NSWRL/CRL suggests they move to Newcastle. Newcastle Magpies start operations in the mid '80s, then Norths move to Gosford.
So, by the time the league is ready to expand interstate, it still has 12 teams, with a better state-wide spread.
Then add Brisbane, Melbourne, North Queensland & Auckland (Sorry Gold Coast), to make 16 teams, and move some Bulldogs home games to Campbelltown to make them a similar west/south-west team to how Wests Tigers
Well, you pretty much have the current competition footprint, just with Central Coast included in the 16 team line-up instead of Gold Coast.
There would still be the same pressure on the remaining Sydney clubs (in this case Souths, Easts, Bulldogs, Parramatta, Manly, Cronulla & Penrith)
I see no reason to believe that the Sydney clubs would have been more willing to move to regional locations such as Canberra and Newcastle over bigger cities further away.
When you are totally adamant that you won't move out of Sydney at all, you aren't considering possible locations and which would be better.
Before you say it, yes the Bears did agree to move to the Central Coast, but firstly they are the exception that proves the rule, and they only agreed because they bordered with that region and thought that they could still connect with and control the NS market from the CC, something that wouldn't have been possible in most other cases.
On top of that they only agreed to move because they thought they had a promise that if they relocated they wouldn't face the axe when rationalisation came.
I also suspect that they always intended to slowly phase out their representation of the CC in the long run. Basically they'd do what the Dragons have done in the Gong; Base the team there, but play the majority if not all of their games out of NS Oval. So basically it would have been more a relocation in name only.
I also think that Sydney teams relocated to regional cities would have been much more likely to be rejected by the locals and to fail as businesses.
Most people in the regional towns that we are talking about would only follow a relocated team from Sydney if they already supported that team.
Take me for example, if anyone other than the Bears had relocated to Canberra/Queanbeyan then I wouldn't have followed them, I'd have stayed a Bears fan and only gone to games very casually or when the "Canberra Jets" were playing the Bears.
In a big city that's not a problem because there're plenty of fish in that pond, but in a smaller regional market (particularly back in 80s) to support a local team you needed as much of the local RL community to be behind the team as possible, otherwise it was going to go broke very quickly.
On top of that, all the successful regional clubs in the NSWRL/ARL/NRL have been built on strong leagues clubs, and if the clubs that were relocating out of Sydney had strong leagues clubs then they wouldn't be relocating out of Sydney in the first place.
If Newtown relocated to Canberra they would have struggled just as much as they did in Sydney. It might have delayed the inevitable, but that's all it would have done.