I knew Tokitou was done since he was cut in half and didn't have demon powers to regenerate, but Genya's death really took me by surprise, I didn't knew Gotouge would be bold enough to kill him, but here we are..
I'm going to be honest, I actually kinda disliked Genya at the beginning of the series. He looked just like another Bakugou-like angry, extremely rude character (with the same voice included) and I hated how disrespectful he was with Ubuyashiki's child. I thought I wasn't going to like him much until I read the Swordsmith village arc, when he developed to a more humble and nice character and grew a genuinen friendship with Tanjirou and left aside his ambition to be a Pillar to help Tanjirou defeat Hantengu. It was a this time when I started to like the character, and with the reveal that he wanted to bond with his brother after he regretted insult him made him become one of my favourite characters. So, seeing him die as he tearfully disintegrates and tells farewell to Sanemi was a huge punch in the gut. I don't know what to think, really. In one hand, it's nice to see that Kokushibou wasn't a joke and managed to kill two named strong characters, but on the other, I really wanted Genya to live...
Now I got clear that no one is safe in this arc. Himejima is going to perish for sure, and Sanemi has huge probabilities to die too, as he has lost everything and he doesn't has anything else to lose. I don't know about the rest, but I'm also fearing for Kanroji and sneak boy to die too. Please spares them at least, crocodile-sensei.
At this point it's hard to really say who safe. I thought some characters would be safe like the 5 senses but Gotouge obviously proving me wrong if we thought that these characters would be protected by plot armor
The only characters in my opinion that are "Safe" are
Tanjiro
Inosuke
Zenutsu
Nezuko
Kanao(Maybe)
I guess maybe if you want to thow Kanao in there go ahead, but from the looks of it, it dosent really look like she'll make it far with her eyes like that but hey I could be wrong.
As for pillars, no one is safe. Would I really be surprised if ALL pillars are dead by the end of this arc not really. Gotouge made it pretty clear that she inst afraid to cut fan favorites or major story characters, and I dant think we'll ever get a Bleach situation again of when you kill a character and people would riot and send you death threats that you then decide to bring them back(Fuckin hell that was insane). Now, who has the best chance to survive by the end of this? i'm gonna list them down on a scale from 1-10, 1 being, no way, 10 being they'll be aight.
Gyomei(1)
Sanemi(2)
I mean, do these two even have a purpose being alive after the arc? and Gyomei having that demon slaying mark dosent help either, I think they will both give major contributions in order to defeat Muzan, but then Die trying leaving the rest to the 5 senses (minus 1)
Iguro(?)
I mean, even at this point of the series and we know jack squat about this guy

I guess if you want one of you're ships to sail with Mituri then OK, but we don't even know how powerful he is. For all we know he could be the most powerful demon slayer, or even the weakest if he relies on poison like Kocho does and is by far less quick, so we'll see.
Giyuu(50-50)
Mitsuri(8)
These are by far the fan favorites of whats left of the pillars so if any of these were to die then I get the feeling the Fan base would riot. I mean, imagine these two dying and the other 3 surviving. OOOF. but anyways back to the list. Giyuu death flags have been everywhere, I mean for one, his sword is broken so I don't know how much fighting he'll be able to do with his condition. He nearly died against upper moon 3 had it not been for tanjiro, but that a debate for another day. Mitsuri...... Usually if we're doing this based off of right now, Mitsuri like, a 0. She already proven that her battle IQ isnt the hightest and that she kinda just bursts into battle without realizing their weakness or abilites. If Mitsuri makes to Muzan with that sort of mind set, she dead, like, REAL dead. But I think Mitsuri will somehow ougrow that nature of hers which will allow her to defeat Upper Moon 4.
If I had to take a wild guess on who gonna survive out of the pillars then I guess it would be mitsuri. I mean WHY?
Why would you kill her? I don't know what the purpose would even be story-wise or character development-wise, maybe I guess for Iguro so that way he maybe awakens something like his demon slayer mark, but other than that her death wouldn't make sense.
Giyuu is a close second on surviving but his death could probably help character development-wise. His death could probably help Tanjiro awaken the breath of the Sun and defeat Muzan.
Also if Mitsuri is the only Pillar to survive then MitsurixZenutsu

