Whilst I agree its the bit part players that need to move on first, I wouldn't be that surprised if we release Garbutt and/or Parcell, as Furner seems to be working to recruit higher standard NRL players than we've seen for a long time, and right now we're in a sweet spot where NRL clubs are making last-ditch attempts to sign players, meaning other have to move on due to cap issues (Titans and Storm seem to be doing similar).
I'd also add that Sinfield was clearly not impressed by a lot of things on his return, and that could include a number of senior players, and Furner no doubt watched as many games as he could from last season. I doubt many players would come out of that looking good for a new coach aimed at winning trophies.
Walters' Wiki page (yes, he has one) says he's been released from his contract. Could be wishful thinking by whoever edits that page mind you....