Yeah it gets tricky when thinking of other names. I think the Haruna thing is based purely off of her age, but honestly I don’t think she’s going anywhere unless she decides she wants to get into modeling or something, but I doubt it. Haruna is in for the long haul. When she was in High School and had to say what she planned on doing after graduation, she answered join Morning Musume... that was before there was even an audition. She literally has no other plans. She mentioned more recently in an interview that if she wasn’t in Morning Musume she’d be professionally unemployed. That to me is a girl who plans on staying until her mid 20s and only leaving to become a housewife or something.
Akane looks up to KonKon. She may leave for college one day, but I think she wants to juggle both and stay in Morning Musume until graduation my guess.
Sakura (who better not graduate) could potentially graduate for a solo career, but like Airi is probably in it for the long haul.
Mizuki is an HP superfan who I can’t see leaving earlier than 10 years like Risa, everyone says Erina probably will leave because she’s been notoriously unhappy and unconfident which comes across as her not giving 100% but really she doesn’t have much else to fall back on so I don’t see her leaving. (Unless she just wants to leave entertainment altogether and go back into everyday life?)
Misaki might leave because of a flare up of her injury (which is why I think she’s been looking upset tbh)
Ayumi ??? She’s like a professional idol. I don’t see her leaving. Unless she pulls a Riho and wants to dance abroad or whatever.
13 Ki just joined so they have a while, but Kaede took so long to get in the group I think she will stay until the last possible moment.
Too early to call for Yokoyan and Chiichan but my gut says they will stay a while