Hansen replaced Henry as Wales coach in 2002 and is tipped to take over from the ex-British Lions coach after this year's showpiece event in France.
But the forwards specialist remained diplomatic, saying: "There's a process the NZRU (New Zealand Rugby Union) have got in hand and they'll work their way through it.
"It's important that they've got an idea of what's happening next year but I don't know whether it needs to be a public thing.
"Whether it's someone leaving the coaching set-up, or if it's someone outside this coaching set-up who may have the opportunity to be in it, they'll all get informed of what the process is."
All five Super 14 coaches are also available at the end of the current season, while provincial coaches Warren Gatland, Aussie McLean and Pat Lam have also been linked with the role.
Hansen expects any potential rivals to stay in the country until after the the World Cup.
"Clearly you wouldn't want people leaving to take offshore contracts if they were interested in the All Blacks job," he added.