McKenzie, who plays at fullback or flyhalf, has been a key figure in the two-playmaker structure New Zealand has fostered in recent seasons.
However, Hansen said an agreement with New Zealand Rugby and the five Kiwi Super Rugby franchises around the foundation days - another will be held in Auckland on May 20 for the North Island players and in Christchurch on June 3 for the South Islanders - meant only those involved with the All Blacks previous year could be included.
"He [Moli] is a player that we're really interested in and we just want to see where he's at", Hansen said.
"His World Cup opportunity's gone but he's still young enough to make probably the next two".
"It's sad for him obviously".
The Chiefs fullback was helped from the field in the second half of the Chiefs' win 33-29 over the Blues in Hamilton on Saturday. It creates another opportunity for somebody else. "We've got to expect injuries and there will be more than just him I'd say".
McKenzie has carved a successful career out for himself as a utility back, while he plays mostly at full-back he can provide cover at outhalf and is often a spark of creativity in the New Zealand team.
Hansen said the selectors had made a decision to invite only players involved in the All Blacks' 2018 campaign.
He was picked as one of the 41 players to attend today's All Blacks foundation day in Wellington, and was highly likely to be one of the three first-fives selected for the World Cup, along with Beauden Barrett and Richie Mo'unga.