The owners have maintained they have no intention of letting the club go - despite speculation over investors preparing bids.
Recent reports from the Middle East suggested that the Qatari royal family is preparing a £1.5billion bid to buy United.
Family affair: Avi (left) and Joel Glazer watching United at Old Trafford
However, Edelson, a non-executive director at Old Trafford since 1982, said: 'It is inevitable that at some time they (Glazers) will sell, but that will be a long way down the line.'
Edelson has no duties on the board of Manchester United Ltd or any of the Glazers' Red Football companies and his role is, in reality, a powerless position.
Speaking at a private event in Manchester, it is believed that Edelson also said that the Glazers would sell 'long after I am dead' and that it could be another '20-30 years' before the family chooses to cash in on its asset.
The Americans are confident they can alleviate much of the club's debt by clinching a world record kit deal worth more than £450million before the current arrangement with Nike runs out in 2015.
Manager Sir Alex Ferguson has also been told funds will be available to bolster his playing squad.
The club is worth an estimated £1.8bn.
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