The only REAL untouchables for me are Datsyuk and Zetterberg. Kronwall might also go on this list but not to quite the same extent. Obviously, I include these players in this group out of loyalty and Red Wings culture. I wouldn't trade them unless they wanted to be traded (which is extremely unlikely).
But after that, virtual untouchables would be Larkin and Mrazek. It'd have to take a hell of an offer (i.e., massive overpayment) to part with those two.
Everyone else is available for the right price IMO.