The players were told as much after Saturday night's 30-point loss to North Melbourne in their final home and away game of season 2014.
It has been a disappointing season for the Demons who only managed four wins, two of those coming against top eight sides Richmond and Essendon.
With several players playing for their careers over the past month, Roos said list changes were necessary to continue the club's development.
"Every player is tradeable in my view," Roos said after the loss.
"We'll try and get the best list we possible can moving into next year. We need to improve and we need to find avenues to do that."
Dees and Dawes all done
The Demons are expected to be major players in the upcoming October exchange period.
Last year Roos' aggressive approach saw the club trade picks No.2, No.20 and No.72 to the Giants in return for young gun Dom Tyson plus picks No.9 and No.53.
"It's always an interesting period," Roos said.
"We just want to improve our list. Dom Tyson hats off to him, he's had an outstanding season in a whirlwind of criticism. If we can add that sort of talent to our list we will get better.
"We'll try all avenues but it is difficult with free agency as well as you may lose a high quality player, so there's all those challenges. You can only be as aggressive as other teams let you."
Melbourne may very well lose a player to free agency, with defender James Frawley still yet to re-sign with the club.
Speculation over the versatile Demon's future has been rife this season with Geelong, Hawthorn and Gold Coast all interested in securing the services of the 25-year-old.
If Saturday night was Frawley's final game in the red and blue, Roos was none the wiser.
"I really don't know [if it was his last game] to be honest," Roos admitted.
"James has been really good. He's been really engaged with the group, there's certainly been no signs that he's put the cue in the rack.
"He's been good around the club, trained hard, played to the last minute and that's all I can ask. If he does leave, we wish him well. If he doesn't we'll be rapt for him to stay.
"We'll continue to have discussions with him so I've certainly got no complaints and I really don't know either way."
One thing for sure is Roos is upbeat for next season, declaring the club essentially has a number one draft pick up their sleeve with power forward Jesse Hogan still yet to make his AFL debut.
The 19-year-old has been sidelined for more than five months with a back injury and made his return to competitive football through the VFL last weekend.
Roos is excited by the prospect of having Hogan in attack in season 2015.
"That is a real bonus for us going into next season," Roos said.
"We haven't had Jesse all year. We don't want to put too much pressure on him but maybe [the injury] is the best thing that's happened.
"He's got a man's body now, he looks like an AFL player. He hasn't had the pressure of a Jack Watts or [Jack] Trengove or a [Tom] Scully. He's had a year he probably wants to forget but it might turn out to be the best thing because we end up with a number one draft pick going into next season, that’s two years into his craft.
"We're well aware we've got a high quality young forward coming into the team. He'll have to work his way into the team."
