The former Manchester United star resigned from his first managerial job in December, with Sunderland sitting in the Premier League relegation zone.
Keane had led the Stadium of Light outfit to the Championship title in 2007 and his former Republic of Ireland team-mate Quinn believes that will always be remembered in the North East.
"We miss Roy," said Quinn.
Shallow"People here are still grieving that Roy is no longer here. The game is a shallower, lesser place - the Premier League especially - without him and I do think he will be back.
"Roy Keane in his pomp here - there was nothing better. He won the Championship and got in to the Premier League and for that he will always go down in folklore up here.
"You will hear nothing but good things from people in Sunderland about Roy Keane."
Quinn also admits he is gambling with his reputation as a chairman by slashing season ticket prices at the Stadium of Light.
"It is a risk," he added. "We have taken that choice for the team and supporters of the team and (have chosen) full houses as opposed to maintaining income levels. But I will stake my reputation on it."