Humphreys has qualified to represent England at the 2026 Rugby League World Cup.
"The IRL has qualified him," England head coach Brian McDermott said.
He is close to signing a multi-year South Sydney extension beyond 2027, according to The Daily Telegraph.
His future was uncertain beyond 2026, but he rejected a Perth Bears offer in July despite interest from two other Sydney clubs.
Salary-cap constraints have complicated the Rabbitohs' final three roster positions.
Payne Haas joined on a seven-figure deal, while Latrell Mitchell, Jack Wighton, Campbell Graham and David Fifita also command significant salaries next season.
South Sydney is close to extending Cody Walker for 12 months in 2027, although he remains unconfirmed.
Walker and Humphreys would fill 29 of the club's 30 roster places for 2027. Adam Elliott also wants another season.