Australia Jillaroos coach Brad Donald has suggested further changes will be made to the national side with a focus on the 2021 World Cup after he re-signed for a further three seasons on Wednesday.

Donald will lead the Jillaroos into a new era of women's international rugby league, one that includes the inaugural international Nines tournament next October.

The Jillaroos are undefeated under Donald's tenure, which began in 2016 after he replaced the late Steve Folkes, and includes World Cup success in 2017 and Auckland Nines tournament victories.

"I'm over the moon, to sign up for the next World Cup I'm really grateful," Donald said.

"When I stood here a couple of years ago I didn't realise I was just coaching a footy side but I was facilitating a movement. That involves fans, the media, playing group and staff.

"We're at a very opportunistic time to ensure we grow the game properly so we need a lot of care. The playing group are strong about that and with my job at the NRL and as Jillaroos coach I can facilitate that."

While age has proven to be no barrier for women's sides in the past, Donald said the coaching staff had acknowledged a revamp of the squad was underway ahead of their World Cup defence in the United Kingdom.

After blooding five debutantes in October's Test against New Zealand to help combat their World Cup final average age of 28.6, the new average of 26 could drop further.

There's been evolution from the team since the time we took over Jillaroos coach Brad Donald

Jillaroos prop Heather Ballinger has already announced her retirement, while the long-term futures of veterans Ruan Sims, Elianna Walton and Steph Hancock will be up in the air ahead of the World Cup.

Classy Broncos pair Chelsea Baker (32) and Ali Brigginshaw (29) and Queensland captain Karina Brown (29), could also be entering into their final World Cup campaign in 2021.

"There's been evolution from the team since the time we took over," Donald said. "In May last year we dropped our captain of the team in Steph Hancock because she didn't reach standards. She came back better and held the World Cup trophy aloft.

"I was keen before the game in New Zealand to make some changes, I knew if we were going to look at the World Cup campaigns we need to look at a four-year cycle. We took some great young rookies.

"I think you'll see more changes, we saw some exciting new talent in Hannah Southwell, Keeley Davis and Holli Wheeler come into the side."

Match Highlights: Kiwi Ferns v Jillaroos, 2018

Donald will keep an eager eye on the Kangaroos' international calendar for next season, with confirmation to come on the women's schedule.

"We're committed to trying to do everything men do, we want to make sure we've got opportunities for our players to play international rugby league," he said.

"If we can put on a high-quality NRLW and back that up with some international content then that will be a good thing for the game."