Maybe, I guess we'd find out soon enough, too.
The new cast seem to be all "new people" though...maybe Nanaka looks just like Kotori, Yume looks just like Nemu, Maika looks just like Mako and so on (actually that's it)...but they all seem to be "themselves" personality wise despite the connections (like Minatsu hating bananas ^^; ), and that's a good thing.
So I don't think the people from the last generation will overshadow the new cast even if they do end up having lots of influence in the storyline, since the new cast shines by itself.
I liked Koko too. She seems to be a pretty sweet, innocent airhead, certainly she'll have lots of comedy value. Nanaka is actually one of (if not -the-) my favourite stereotypes in all of bishoujo gaming - I think I might end up liking her even more than Kotori (I liked Natsuiro no Sunadokei's Mana, Ever17's Sara, etc.).
And Yume's funny and...what would you say, "lolicute"?
. Otome? I think there's lots more to her than what we've seen...I still can't forget that 4koma ^^;. Oh and regarding Anzu, she's a little...scary.
Yeah...definitely the new characters are just as good and interesting as the originals, something I was slighty concerned about - whether they'd keep the quality that high character wise.