Guaranteed untouchables? Dutchy, MacK, and Landy for sure. ROR only because he can't be moved just yet. (for the record, I doubt he will be unless it's for a top-4 D that can play with EJ)
Varly might be only because there really isn't much of an option in net ATM. Same with EJ - not too much of an option on D.
Barrie probably. Young D, taken several steps forward the last few years. Doubt he'll be moved.
Staz for the moment only because Roy sees him as part of the core.
PAP for the moment because of the chemistry with Dutchy.
McLeod and Bordy because management seems to be in love with them.
Tanguay and Hejda, vet voices in the locker room. Not to mention Tangs has the history with management and Hejda's pretty much our only consistent D. Moving him wouldn't make too much sense IMO.
That being said, those ones I mentioned as possibly being untouchables could be moved for that perfect package, like Tigervixxen said. Just unlikely ATM.
Pretty much everyone else is fair game IMO. Wilson, Elliott, and McGinn could be moved for the right pieces. I'd rather not see them go, but if they brought back pieces who are consistent I'd live with it.