I believe Saki 2 is a distraction and while we all worry about history repeating instead Itsuki will be murdered, especially after raising the death flags of giving up smoking for his health, and talking about his adopted daughter and the grandkids last chapter. I'll even go one step further and say that the killer will make a crucial mistake regarding cigarettes/ash since they'll see Itsuki's fake cigarette and ignore some evidence/say something odd at a key moment.