I really like your suggestion of North to Canberra and Perth 3. I think both of these markets are underrepresented and this would kill two birds with one stone but unfortunately it’s not going to happen.I'd only be for moving into new Zealand after the giants are at the swans current level and the suns are well established too. Meaning Australia is mostly tied up with strong teams everywhere. They'd be biting off too much going there at the moment.
I also have concerns about the kiwi publics disdain for Australian things.
A pity because if it did, they could have the Hawks maybe split Darwin and Cairns 2 games each to cover top end, Saints cover Auckland, and Giants or Dees play a game in Newcastle.
Could then post 2050 look at another round of expansion if as you say you have 20 strong clubs by then. Because if you don’t, then leave it on 20 teams for as long as needed.
I think in 50 years time the AFL could support 24 teams but they’d have to do it from a position of strength and not have 4-6 clubs on life support.