I mean didn't Momoki literally tell us she wasn't going to die? She said all of her senses would disappear and the only thing left would be her heartbeat. She's just going to become a blind, deaf, mute, quadriplegic. Granted that leaves out her lungs which are pretty important too but let's pretend for a second that "only her heartbeat" includes the entire cardio-pulmonary system since they are so closely linked.
Also Reo finding that mummy makes a bit more sense now since that baby husk could be like a prototype for Momoki's poison and maybe lead to a "cure" or something. We know the author is a hack so the Reo B plot could lead to no where and it's just to keep her relevant in the reader's minds so he can inevitably have HER brutally murdered as well but maybe the author got a sudden surge of insight into how writing a story actually works and it is indeed setup for a payoff later.
I feel Azuma is too much of a fan favorite (if you can call the people still reading this fans) to just off her before the other remaining girls who are significantly less important or impactful. If Azuma is actually dead, why should anyone care about the others? Azuma was the only one people gave maybe an iota of a shit about and was here against her will (blonde nurse girl Kawana is fine but she chose to be here).