Ai-chan- I don't want her to leave at all but she is the leader and of course the leaders must graduate to continue on with tradition. She has the best voice (to me) and probably would continue on with a solo career or doing plays and dramas since she is really into that.
Risa-I don't think she will leave right now because she has loved MM ever since she was little and probably really wants to be leader even though she didn't say she did on latest music fighter episode. I think she will graduate after Ai-chan/someone else.
Eri-I have wanted an Eri solo since I heard Haru beautiful everyday but personally I don't think she would want a solo career after all she is still a little shy/timid and doesn't really speak up that much. I can see Eri being sub leader and maybe leader one day.
Sayu-Really doubt she will graduate she seems to be wanting to prove herself more in MM and wanting a chance to sing so I don't think she will leave for a while. At first she was all about the cute thing and now she is really maturing which i like about her
If she were to graduate she would probably become a TV talent like Mari.
Reina Don't really think so since they are pushing her in front A LOT lately. She already is a front girl in MM and when Ai-chan leaves she will probably continue on being the front. Unless Tsunku has a solo plan for her I don't think she will be leaving.
Koharu No way she is the face of MM right now and probably after Ai-chan leaves will become the front girl with Reina. She is popular with kids so thats just an added bonus for MM. She is already a soloist but once the anime is done I don't see her leaving I see her stay in MM.
Aika/Jun/Lin-No way since they are the new generation. Jun/Lin haven't really been featured in songs much so it will be a long time before they grad.
So I think Ai-chan will leave but I don't think anytime soon since MM is really busy with their concerts and the Cinderella play but maybe afterwards they might announce her graduation.