Anthony Joshua could call time on his boxing career "at the end of 2026 or even next year", according to promoter Eddie Hearn.
The British fighter, 34, is bidding to become a three-time heavyweight world champion and his next fight is scheduled for Wembley on September 21.
Joshua could fight for Oleksandr Usyk's IBF title if it becomes available before his rematch with Tyson Fury.
Matchroom promoter Hearn revealed that Joshua is fighting for "legacy" and "greatness" before his professional career, which started in 2013, comes to an end.
When asked how long Joshua has left in the sport, Hearn told the PA news agency: "I think maybe the end of 2026.
"If he wins in September and beats Fury or Usyk to become undisputed then what else do you do?
"It could even be next year, who knows? He'll want to continue while he's performing and right now he's the best ever.
"He wants legacy, greatness. If you asked him, he'd also want to have good performances."
Daniel Dubois, who recently stopped Filip Hrgovic in Saudi Arabia, would be the "frontrunner" to fight Joshua should the IBF belt become available, according to Hearn.
Hearn admitted the 21-2-0 Queensbury heavyweight would be a "dangerous" match-up for Joshua.
"The preference is for Joshua to fight for the world heavyweight title. If the IBF title comes on the line then Dubois becomes the frontrunner," Hearn added.
"He's a dangerous fighter. He's always been a good strong fighter and now he's maturing as a man and he's got massive confidence.
"It was a good win against Hrgovic, I didn't expect him to win that and he's now positioning himself to fight for the world heavyweight title. So it's a dangerous fight between two Brits.
"A lot of it comes down to conversations with his excellency (Turki Alalshikh) to work out that situation. If we get told that you can fight Dubois for the world heavyweight title at Wembley then that becomes appealing."
Joshua's second-round knockout victory over Francis Ngannou in March extended his winning streak to four.
Hearn tipped Joshua to recapture his belts, backing him to beat anyone in the sport to do so.
When asked if Joshua could become a three-time champion, Hearn said: "For sure. He's in the best physical and mental condition of his career so far and at the moment he beats everyone in the sport."
