Hello Michael, I don’t think it would bother me as a reader if a first person narrator didn’t make it through to the end when you’ve got other POV characters to continue the story. But it would depend on the novel. Things could fall flat if, say, the most compelling character disappeared. But I imagine you’ve thought of that already.

I wonder if there’s a second question here. My opinion is very inexpert but I think a mix of 1st person narrators and 3rd person viewpoints can make the 3rd person characters appear less significant; they have less weight. This may be OK for your novel. The people who aren’t going to make it could be the less important ones anyway. However a little warning voice is suggesting that several POV voices and a 3rd person voice/voices is starting to sound complicated. I shall sit myself on the nearest handy fence and say, do you know of published examples where what you’re proposing has worked well? If yes, then great. If no, then – well maybe see what other people say first.