@REP
in the final scenes of a story, the MC is dying. Once the MC is deceased, the first-person narrative continues as if the MC is still narrating what happens after their death. Obviously that is not possible.
In most stories of this type, the reader is not informed of who is providing the narrative. It is also true that the speech pattern and the speaker's point of view continues to be that of the MC.
Using the example in Switch Blayde's post:
The last sentence of the novel is: "I smiled, exhaling one last time, never hearing the priest's response."
That is merely an "unreliable narrator" as we have no idea if the priest actually responded or not. It seems that the MC is presuming that the priest would respond.
It is completely valid in a story for a character to anticipate what may occur. Perhaps the character is correct, or perhaps not.
We cannot know what our last moments will be like, until they occur.
However, I did experience being rendered unconscious by an IED blast a mere few meters away (under the front axel of an M1114 "up-armored" HMMWV) and I had a series of distinct thoughts, and was able to observe the fireball expand over me and the other personnel aboard the vehicle. I have solid professional knowledge of the speed of an explosive blast.
Thoughts may be processed at incredible speeds. I had an experience followed by a period of utter blackness. Nothing has been more surprising than waking up alive!!! It was surreal, as we were in an uninhabited area, and my unit was practicing noise and light discipline; so, I was not at first aware of where I had regained a degree of consciousness.
I now grant a greater degree of tolerance for a character experiencing final thoughts in a story.