The captain suffered a hamstring injury playing against Leigh earlier this month and had been expected to be ruled out long-term.
Coach Lam has now confirmed that and it immediately sparks the question: Will he play for Wigan again?
The 36-year-old, in his second spell with the club, is out of contract at the end of this campaign.
It is unclear whether he will play on for another year or retire and take a coaching role.
Coach Adrian Lam said: "I think that process will happen over the next month - that's his decision with the club."
Fellow halfback Jackson Hastings is leaving to join Wests but Wigan still have Jai Field and Harry Smith under contract for next year, and haven't signed any reinforcements to play in the halves.
Leuluai has longed been tipped as a future head coach.
His ex-Wigan team-mate Sam Tomkins recently said: "I have good friends who can dissect the game unbelievably.
“Tommy Leuluai could be coach of the year next year if he got a team, I truly believe that. He is smart, watches games, talks about the defence you are playing against. Tommy will dissect everything."
Bevan French is also out for the season with a hamstring injury and is currently rehabing the injury at home in Australia.