I'd be surprised if the Bombers move on from O'Shea or Walters. In the last 6 seasons, they have made the playoffs each year, they were Grey Cup Finalists 5 times and Champions twice. They finished with a winning record this year. The Bombers could and likely would do a lot worse by replacing these guys.
They have stayed loyal to some long time vets, some for maybe too long, and their play has clearly dropped off. I'm not sure if they should move on from Collaros, but he is not the player he was a few years ago. Jefferson is not a dominant defensive player anymore. Neufeld and Bryant aren't what they were. They'll add some free agents, but it is in the new recruits that sets a team up for success.