We're not talking now. The season is over. We're talking December or January. By then we're likely to be back to Level 1 (I hope).
Of course it involves international travel. Even inter-state travel to Western Australia or other Australian states involves a 14 day quarantine period, so who cares if it's in Australia or NZ. Plus once you have done the two weeks then it's 8 weeks of living more normally. Australian teams can even bring their WAGs and kids.
Quarantine facilities can handle 7000 returnees a week. I am sure 7 squads of 20 (max 140-200) people is the equivalent of one medium sized interantional flight.
No-one has any idea what December is going to look like, here or in Aussie. The situation changes so fluidly - all you have to do is look back at how things were in January/February, and then in March/April, and then June/July, and then now, to see that trying to predict how exactly it's going to be in December is a fool's exercise.
There are basically two realistic options:
1. Start season in December in a centralised, most likely NSW, hub for all teams and re-evaluate if circumstances allow
2. Delay the start of the season until February or later, and hope that by then the situation will have normalised (and have a centralised hub option as a back-up plan).
Planning for anything else is unrealistic, because quite frankly no-one knows what's going to happen and when.
NZ quarantine facilities can't accommodate 7,000 returnees a week. NZ quarantine facilities have maximum capacity of 7,000 at a time, and that's unlikely to increase as no additional suitable facilities have been found. And that is not to mention that those facilities are designed for returnees to the country who largely stay in their rooms and spend a short amount of time outside within the hotel premises to get exercise. Such facilities are not suitable for professional sports teams who need to train during their quarantine time.