"ERMMMM ENGEL GOES INTO HIS ANGST PHASE, KILLS THE BULLIES, KILLS THE BAD TEACHERS, KILLS ALICE AND-"

Shut the fuck up.

‎

With that out of the way, seriously, what would happen?

(All of this is theoretical since Basics in Behavior is non-canon and that Kaaatieverse is entirely dead especially with Kaaatie herself leaving so take everything I say with a grain of salt)

Paper School

If whatever city or town Paper School is located in, the school may get shut down because of the 3 students getting killed off by 3 cannibal and murderous teachers and a literal demon residing in her own forbidden chamber of doom.

This entirely depends on weather or not Paper School is capable to keep all the students' mouths shut out of fear for whatever reason and practically force them into gatekeeping, or if the police are just really corrupt.

Abbie's, Lana's and Claire's friends

This is assuming if the deaths of Abbie, Lana, and Claire.

Canonically speaking, Abbie and Lana haven't made any friends for all we know, so we can immediately ignore these two.

Now for Claire? Engel and Bubble would sure as hell be depressed, but assuming the school has been functioning for a while, they may get over it in rare cases. If Bubble getting eaten alive later on by Oliver/Katie in a joke artwork is considered canon, Engel would sure as hell be more depressed than he'd ever could be, and from there, it really depends on his mental health.

Biscuit and Anova would certainly be devastated by the news since Claire was their best friend, Anova would probably even go as far as committing suicide as official artwork already depicts her of thinking of or using a noose to hang herself.

MoeMoe, being Claire's pet, would either get abandoned within Paper School entirely (considering we see him in Miss Circle's classroom at some point), will (assuming that Claire has any parents) still be kept by Claire's parents, will just be left out entirely or will get adopted by anyone else.

The rest of the people that Claire may have good connections with, those being Daniel and Snowie, would certainly be saddened by the news.

What would happen to Oliver/Katie and Zip?

We see at the end of Basics in Behavior that Oliver/Katie and Zip are the ones to craft and put a fake exit sign on the door to Δlice's room, which eventually lead to Claire's death, we see Miss Circle, Miss Bloomie and Miss Thavel looking upset, most likely because of how dangerous Δlice is.

Considering that both Oliver/Katie and Zip (along with Edward) are the 3 teacher's favorite students, probably nothing bad would happen to them. Worst case scenarios would probably be that Oliver/Katie and Zip may get detention, but nothing more.

The other students, specifically the students that find out about Claire's death

Mixed reactions, sad emotions, entirely depends on their mental stability, whether they're sane and if they're sneaky, they could snitch on their parents or the police.

Literally everything outside of Paper School

Assuming that everyone has heard about the 3 students deaths, mixed reactions would appear.

Some, such as F.E.N and The Nameless Werewolf, would probably feel some kind of twisted sense of satisfaction.

Miller's gang? They probably wouldn't care, except for maybe Agetha, but even then we don't know her exact canonical relations with Claire.

As for everyone else? We can't tell for sure in some way.

I'm gonna go to sleep rn otherwise my mom will get mad at me.

Seyaz!