@Fixided
Just like how Nezuko turned into a bloodthirsty demon? Just like how Nezuko burned with the sun? Nezuko is pretty much invincible because she's the chosen one for no explainable reason.
One of my biggest pet peeves with the series is how Nezuko has woken up like three different times now to goddamn ghosts being like "NEZUKO! TANJIRO IS FUCKED IF YOU DON'T DO SOMETHING!"
I get that the Author didn't want Nezuko to be dead weight but I feel like it swung too far the opposite direction.
It's funny because I don't even understand her too much as a character, since she feels more like a plot tool.
So nah it's not really optimism, it's more that I believe I know the Author's mindset on the matter. I can't see the Main Characters having a tragic ending, even though it might be suitable.
As an aside, I practically started screaming when I saw Muzan casually revive Tamayo then delete her at the same instance. I fully expected her to make an escape, but THAT moment is where I'm like, OKAY so we can literally revive any demon absorbed by Muzan if the Author wants to (HINT HINT). I certainly hope that Tamayo's death is permanent this time, but it sets a precedence that even IF Nezuko gets absorbed and isn't immediately spat out, that she could still potentially survive regardless because her 'cells still exist'. You might not like it, but the set up is already there.
1) Nezuko could wind up 'controlling' the cells to recombine
2) The Ghosts beg for Nezuko to survive and the cells listen
3) Only has the demon half ripped out and Nezuko turns human
Callin' it