Brown, who starred in last year's Pacific Championships final win over Samoa at No.6, will miss the showpiece event with a ruptured ACL sustained in Newcastle's 23-22 loss to Sydney Roosters on Saturday night.
Melbourne half Jahrome Hughes is expected to be the first half picked at No.7 after he missed last year's Pacific Championships with a neck injury that he carried through the NRL finals series.
Manly coach Kieran Foran played half in Hughes' absence but retired to bring an end to his stellar 34-Test career.
Nikorima played the last of his 18 Tests in 2024 when he came off the bench in a 54-12 win over Papua New Guinea.
The 32-year-old has been in career-best form at the Dolphins where he remains unsigned for next year, and Kiwis hooker Jeremy Marshall-King said he would be the perfect candidate to fill the breach.
"Kodi will do a great job for the Kiwis," Marshall-King said.
"He has been showing the last couple of months what he is about as a player and he will fit in that role for sure. He just needs to focus on his job here at the Dolphins but it would be good to see him back in that Kiwis jersey."
Nikorima, who played in the 2017 World Cup at No.6, has 63 try assists in 77 games for the Dolphins where he has reinvented his career as a starting playmaker after several seasons as a utility.
"It is just how crafty he is. He is not the biggest guy but with the ball you see how skilful he is," Marshall-King said.
"His defence has been great as well and that is something he has focused on.
"Hopefully we can re-sign him and keep him at this club because he is a big part of our team."
Warriors half Te Maire Martin is another proven Test performer who is likely to challenge to be Brown's replacement.
Marshall-King said the loss of Brown would be a massive blow to New Zealand's chances of winning the World Cup for the first time since 2008.
"He will be missed, that is for sure and I just wish him well with his recovery," Marshall-King said.
"He is young and I feel for Dyl with that injury. No-one likes to see people do their ACL and he is going to be a big missing part for the Kiwis."
The Kiwis are one of the favourites for the October/November tournament that will be played in New Zealand, Australia and Papua New Guinea.
The decision by Newcastle and Queensland star Kalyn Ponga to align himself with the Kiwis will also give the spine extra depth and class.
"It would be nice to take the World Cup (trophy) back to New Zealand," Marshall-King said.
"With Kalyn Ponga able to switch his allegiance to New Zealand it is going to make a huge impact ion the team."
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