The pure "expendable" guys are Myers, Kulikov, and unfortunately Perreault. Myers hopefully walks in FA, Perreault will likely garner a pick, and Kulikov will likely be a pure dump.
The next level of "expendable" are guys like Petan and Lemieux. They don't have vital roles on the team, and have been getting passed by other players. They likely don't carry much trade value.
I don't really see anyone else I would call expendable. Everyone is tradeable for the right price, but there isn't anyone I would target to move.
Trouba is the key IMO. Personally, if he was to sign, a lot of things fall into place really well. It likely means the Jets aren't able to extend Myers which is a plus. It also means we have less need to trade a young forward for a D.
Even if Trouba doesn't sign, I think we can get good pieces for him. Enough pieces that we could use those pieces plus something smaller on our end to get a D. We're not moving Laine, and I can't see Connor getting dealt either. Ehlers deal isn't one I'd want to trade either.