Barry, 31, is having one final season in 2009, wants to focus solely on his football and has also stepped down from the club's leadership group.
Sydney has two remaining co-captains in Craig Bolton and Brett Kirk.
But with several of Sydney's established stars like Kirk and forwards Barry Hall and Michael O'Loughlin over 30 years of age, Roos said the challenge facing Sydney was to develop the next generation of leaders.
"I think the challenge at the moment is how do we get the next group of leaders coming through, we've had a really good leadership group and those guys are now getting towards the end of their careers," Roos said.
While the club has yet to decide whether to continue with the co-captaincy concept, dual Brownlow medallist Adam Goodes would appear the logical choice to replace Barry.
However, Goodes will turn 29 before next season and Roos was keen to develop the next generation of leaders.
Asked if Goodes was ready to assume a captaincy position Roos said: "He is probably ready, I suppose our challenge is more the younger group.
"The danger is if we put another 29, 30-year-old (as captain), I'm not even talking about Adam, but someone of that age, it may stifle (the younger potential leaders), so that's probably the thing we've got to think about at the moment."
Fully fit after being sidelined by a hamstring injury for several weeks in the second half of last season, Barry said his body felt fine heading into his final season.
"I've had a really good break and I've started training a bit earlier this year so I'm really focused on my on-field performance and hopefully I will have a good pre-season, I feel pretty good at the moment," Barry said.
He nominated Lewis Roberts-Thomson and youngster Jesse White as potential replacements for him at fullback.
"I was always really keen to keep playing and I still feel I can really contribute to the group," he said.
"And I still think at the moment I can definitely hold down that fullback position and there's no one I am keeping out of a spot."
He said he expected Sydney to be "super competitive" next year and have another tilt at the flag.
Roos said Sydney would look at drafting the best available player with their first pick, the No.12 slot in Saturday's national draft, rather than target a particular position.
Roos noted Sydney had a number of older players like Hall, Barry and O'Loughlin in key positions, but felt they could also benefit by supplementing a midfield group containing other veterans in Kirk, Jude Bolton, Jared Crouch and Nic Fosdike.
