Minor side ramble, but one point I've seen commonly raised that's used to justify Nagant's potential death is that the series should have to teach Deku a hard lesson about not being able to save everyone, and I feel like that's a bit of a weak hook to use for Nagant of all people.
For starters, even though Nagant has an extremely compelling backstory that's hooked us, the audience, I kind of feel like the character is just straight up too new to be the vector for Deku to do this; a character who we've known for 300 chapters. Not counting the prison break, she's effectively been in the purview of the protagonist for 4, arguably 5 chapters. That's a very short timeframe to introduce a character who's existence would basically boil down to making a cynical point about futility.
Secondly, the notion of Deku not being able to save everyone has been simultaneously foreshadowed, and has already happened in the story. To a lesser shallow extent it already did this via Muscular, but at a deeper level, the Shie Hassaikai arc's central theme is all about whether or not heroes are able to save everyone. Mirio is introduced as a person with the ambitions to save a million people, with his story at the time ultimately concluding with only getting to save one. Deku and the heroes put their life on the line to save one girl, and in the crossfire, they fail to save Nighteye. Nighteye himself even put an expiration date on All Might, who's death flags continue to accumulate to this very day, and as recently as this arc got a call back to the time he made the decision to waylay any sense of relaxation because of his belief that there were people who still needed saving. Deku has made a promise that he's not going to let All Might die, and I think the question of whether or not he can save everyone is going to mainly be invoked via him.
I think Nagant may forward the discussion, but I don't think you need a permanent cadaver for that to happen. If she survives this, I think Deku's already got a permanent image of a lifeless body burned into his head, so the trauma wouldn't necessarily be absent just because she continues to live. The potentiality at this juncture can end up having an equal level of impact than the eventuality.