There seems to be this argument going around that you either have to kill Sydney teams to go to new markets (which is not very smart and not going to happen anyway ) or that for some reason the game can’t expand anywhere outside NSW/QLD (which is myopic). Just plan Perth/NZ 2 within the next decade (in whatever order you want) and then decide what you want to do with the 20th team when you get to that point.
A 20-team comp with no system of promotion/relegation carries significant risk.
The EPL has 20 teams. The fans of many of those know full well before a ball is kicked that they won't be anywhere near the top of the table. Finishing in 17th (i.e. just above the relegation zone) represents a successful season. All their games are important. There's consequently huge interest and the stadia are packed out.
Australian RL media and fans have an entirely different value system to judge whether a game is meaningful. Over the course of a season, a 20 team comp will provide fewer games which meet the criteria for meaningful than a 16 team comp. This will have implications for underperforming clubs and NRL popularity overall.
Aussie fans of any sport do not think they've had a good year when their team is 13th on the ladder of a 16 team comp. They will be even more unhappy, and potentially disengaged, if their team is 17th in a 20-team comp. And the media will hammer home the miserable message. All this will mean more NRL fans with a face like Phil Gould.