Full-back Folau, who has Tongan heritage, was sacked by Rugby Australia for a homophobic social media post.

He has played 73 Tests for Australia but could switch allegiance if he sits out three years of international rugby and then represents Tonga at sevens in an Olympic qualifying event.

"The next World Cup, he'd be available for us hopefully," said Kefu.

"It's a long time away, so we'll let the dust settle a bit after his most recent issues.

"We don't even know if he's going to play again. He hasn't indicated where he is going, so we'll wait until the dust settles and then look at those options."

Speaking to the Sydney Morning Herald, he added: "He'd have to sit out three years and then even after that we'd have to re-qualify him through a sevens Olympic qualifying tournament."

Folau, 30, also had his contract with Super Rugby team New South Wales Waratahs terminated following his social media post.

He is taking legal action against Rugby Australia and has filed a case with the country's Fair Workplace Commission, an industrial relations tribunal, claiming his employment was unlawfully terminated.

What are World Rugby's rules over switching allegiance?

If Folau wants to play for Tonga, he could benefit from World Rugby rule 8.7.2.

It reads: "The player will be required to observe and demonstrate a stand-down period of at least three years since the time the player last represented their former union and the time the player first plays for the second union or country, which must be in an Olympic event.

"The player may not represent the second union in any other form of the game until after they have participated in such Olympic event."