We're losing a valuable piece in expansion. People need to realize that. There's zero scenario where we lose the equivalent of a Leipsic again. At most, we can protect 4 defencemen, and that's if we only protect Tavares, Nylander, Marner, and Matthews up front.
Rielly will be protected, and Holl is frankly probably #2 at this point given performance + contract. Which leaves two spots for Dermott, Brodie, and/or Muzzin. Based on age/caphit, and like you said the fact that Dermott, Sandin, and Lehtonen are all left handed shots + we'd free up 5.6M in capspace that could also be used on a replacement. Muzzin is probably the one you expose (though that's also dependant on performances over the remainder of the season to some extent). Kerfoot/Mikheyev would also be exposed, though unless Mikheyev really takes off and gets back up to his point production from last year, I think Seattle would take one of our D.
The only real alternative is trying to trade picks/prospects with Seattle to protect Muzzin, but given how much we struggle to find capspace, trading one of Sandin, 1st rounder, Robertson, etc to try to protect Muzzin, doesn't make much sense to me.