We are currently at 13 teams. Canberra makes 14.
Christchurch and maybe Tasmania could be 15 & 16. Then yeah you need say 4 teams from the NPL leagues ie the better performers, especially crowds and money wise, from this new 2nd tier setup.
It won't happen quickly but it could happen. Though for every successful recent entrant like Auckland you have Macarther and Western U struggling along (crowd wise anyway).
Two 10-team leagues just sounds boring imo. IDK what it was like when the A-league had 10 teams but I feel like we should focus on having a longer season (by having more teams in one league) rather than pro/rel with 10-teams a side
Aleague with 10 teams was odd much like it is with 13. We played some teams 3 times and some twice. All to get a season with more than 18 games per team. Ideally, the Aleague wants to target a season length of 26+ games per team. Which means you need 14+ teams in the league. Assuming Canberra arrive in 2027 the league achieves that.
Having had a 10 team SPL for yonks, I can categorically state it's not the way to go. Whilst we played each team 4 times, it got boring as hell, not helped by the duopoly of course. 14 or 16 is the sweet spot imo.