Noel Gallagher walked out on the band after a backstage spat with his younger brother in August 2009.
But the squabbling siblings' older brother, Paul, has said he believes Irish audiences haven't seen the last of the Britpop band.
And he predicted they will call truce and put the band back together. He said: "I think they've got unfinished business. I think Noel regrets walking out the way he did.
"Liam was always going to carry on and do his own thing. I've got a funny feeling something might happen in the future, in two years time, maybe three."
He went on: "All it takes is two guys to say, 'You know what, I'm sorry, but I love you.' That's all it takes, it's not hard. It's easy."
Paul features extensively in tonight's edition of Guth, a TG4 documentary series which explores the Irish roots and influence of some of the world's top musicians.
The contributors to the show said the Irish roots of Oasis' five original members was integral to their success.
The Gallagher brothers, whose mother Peggy hails from Charlestown, Co Mayo, and father Tommy, from Duleek, Co Meath, had "music running through their family", according to the programme.
Paul said: "My mother reckons the music comes from our granny. She was apparently a great whistler and our father played the accordion and the guitar. There was always music in our family." The oldest Gallagher brother also spoke of the brothers' tough upbringing in Manchester, recalling how their mother used to make all their clothes.
He said: "We knew we were different when we came back to school and all the other kids would have pristine jumpers from the stores and we'd be in our knitted jumpers."
Guth: Oasis, 9.30pm tonight, TG4