For expansion I'd say A 3rd Victorian team (Geelong) 5th NSW side Wollongong a 2nd Queensland side (Ipswich) and Canberra
If if you had a promotion/relegation you could have the top NPL sides like South Melbourne, Brisbane Strikers, Blacktown City etc and also more expansion teams from regional areas like Tasmania, Townsville, Cairns, Ballarat, Bendigo, Gold Coast. Fremantle, Auckland (Travel could be an issue?) and second teams in the major cities like Adelaide, Melbourne and Sydney not all of those regional areas but a few. Perhaps allow promotion/relegation from Second tier to NPL/State Leagues