"We don't know when Alex is going to retire and long may he continue," Gill told The Independent.
Related ArticlesGlazer family refuse to sell Manchester UnitedGlazer family insist Man United 'not for sale'Manchester United finances in Panorama probeGlazers to keep cash in United coffersUnited to plead Hernandez caseFoster criticises anti-Glazer movementBut when he does decide to retire, 68-year-old Ferguson, who has spent 23 years in charge of United, is set to be joined by Sir Bobby Charlton on a selection panel as the club seek a man capable of following him and maintaining the high levels of achievement.
"It will be discussed with Alex, Bobby Charlton and the owners," Gill said.
"I think Alex will be the key. He knows people. He will have a big role in advising and being a sounding board. I am sure we will talk with the owners and look at who is there and determine who we would like to appoint.
"It would be remiss of us not to use the expertise and knowledge that we have."
Gill declined to discuss the names of those managers likely to be in contention, and given the decision could still be several years away any existing shortlist could change dramatically.
He described Jose Mourinho as "a winner", as his record, not only in the past season with Inter Milan, only serves to demonstrate.
However, United would not welcome any approach from the Portuguese manager for striker Wayne Rooney once Mourinho takes charge at Real Madrid.
Mourinho is a long-time admirer of the former Everton player, and told Spanish sports newspaper AS: "I would like to train Rooney, both as a player and how their mentality. But my friend Ferguson can rest easy because it is impossible."
Gill suggested United would discuss a new contract for Rooney, and dismissed the notion of the England forward moving to the Bernabeu.
"He won't go there. He won't want to go there. There may be some noise around it. I don't care," Gill said.