Meow,
This is easy!
If that happened Kanes route would just... ends without start?
About Zack, the author must love him to much to kill him. Heheh
But if in serious way. Probably if that happen he may suffer some accident or die when he discover the serial killer, since....
(Spoiler)
He is the one investigating the murders in the story.
Since the story is around 70% done I think. I don't expect some other character replacing him in the story. That naturally use thappen by someone close to a character continuing the investigation.
(A last though I had is about the lion. Thinking about the girl that people think he raped could be one of the murders, since the girls just disappeared from everywhere I think. In this case he pretending he is innocent in the raping when in the real he killed her.)