If Australia bid for the 2030 FIFA Men's World Cup and were successful there maybe some new grounds and serious upgrades to others that would be used for training purposes.
New Zealand could be a co-host as they are for the FIFA Women's World Cup in 2023 although they have only one ground currently that meets the minimum capacity criteria.
48 countries will be competing from 2026 onwards - 8 groups of 6 teams
Stadiums must have a capacity of at least 40,000, stadiums hosting quarter-finals must have a minimum of 60,000 and those hosting the opening ceremony or final must have a capacity of at least 80,000.
Grounds with 40k and above capacity in both Australia and New Zealand
Adelaide oval - 53,000
Suncorp - 52,500
SCG- 48,000
Allianz- 45,500
Gabba - 42,000
Marvel - 53,359
Homebush - 83,500
MCG- 100,024
Perth Stadium - 60,000
Waverley Park- 72,000
Eden Park (NZ) - 50,000