Again this is just a guess at what's going to happen, but from the tone of this story I think friendly destroyer losses are going to be inevitable.
In storytelling terms Calder is good candidate because of his aforementioned grudge with Steele for Jupiter, his diminished resources, and like people have said above because going out in a blaze of glory sounds amazing. Byrne is also a good candidate because of his relationship with Project Shambhala which is implied to be something sinister or at least dangerous, and his downfall could be tied to the downfall of Shambhala if that occurs in the story.
Netreba hasn't recieved as much attention as Calder or Byrne so I feel he's a bit safer.
Also, just because Laporte is stationed on the Toutatis doesn't mean it won't be destroyed, we did lose the Galatea and Psamtik in FS1&2, and Laporte has switched ships at the end of every act so far.