The IRL Board extended eligibility across men's, women's and wheelchair rugby league to players with a parent, grandparent or great-grandparent born in their chosen nation.
The Cook Islands, with a population under 20,000, proposed the change to widen smaller nations' player pools.
Unanimous board support opened talks to promote Tonga and Samoa to Tier 1 alongside Australia, England and New Zealand.
Both reached the 2026 semi-finals; Samoa made the 2022 final, the first Pacific nation to do so.
The 2030 men's and women's tournaments expand to 12 and 10 teams, from 10 and eight in 2026, in a Magic Round across five Pacific and US cities.
The cities are yet to be chosen; pool matches will move between locations over three weeks, followed by semi-finals and finals in a five-week tournament.
The Wheelchair World Cup will run concurrently, with France favoured to host.
Almost 80% of Premier Sports' international subscriptions for World Cup streams came from the US, a key growth market.