You've banged on about this Sydney-culling idea for years... and each time you've never provided an explanation... how do you expect fans to stick around and support patched-up and merged teams?
I can't see a way of the process working without alienating thousands, sorry.
I think there is your answer. If, for example, Penrith were to be kicked out, they have an attendance of 8000ish. That means the league would lose a few thousand fans others just support new teams.
Then, if Perth were to be brought in, they might bring 30,000 fans to games that have no chance of attending without this perth team. Thats a net gain of 20,000 fans straight away.
These numbers are completely hypothetical, but they show the point. certain teams would give greater value than others.
Now you could argue that we could keep Penrith and still bring in perth, which would be a fair point. But in the situation that we cant add teams, is it worth keeping penrith ahead of perth simply because they were already there.
And even if we do have both teams, is there another potential area (South nz, Adelaide) that has no access to a team, that would give more benefit than the existing teams.
Having said that, you need to decide what you are trying to accomplish with teams. Do you want a team with heritage playing in a dilapidated empty stadiums, do you want new (possibly generic brands) in packed stadiums, do you want shitty quality games that are right near your house, do you want the best talent in moneymaking stadiums.
AND when considering all of this, realise that you are inevitably biased towards certain answers because of your connection, or lack there of, to different teams.