It might be that the idea of the "death of the subject" is really two or three different ideas, maybe six.
We can talk about a sort of blank writing, neutral in tone and de-personalized, arising out of Blanchot and the early Barthes. It no longer matters who is speaking or enunciating.
We can talk about skepticism about the unity of the self (Borges, Pessoa). The self is fragmented, doubled. This gives rise to a plural and hence indeterminate self.
We can talk about subjectivity reduced to its bare-bones. One is conscious and that is all. The immediate situation is what needs to be addressed. Say a character in Beckett who is trying to use his cane to pick up an object otherwise inaccessible to him.
There may be others too. An extreme catatonia: "la cosas la están mirando / y ella no pueda mirarlas." (FGL)
I've mentioned the biographical skepticism of Proust and James.
It would seem to me that if I could analyze all these possibilities and associate them with particular writers, creating a taxonomy of some sort...