I think Cho saw Cedric thorugh Harry, and that's really part of the reason she liked him, if not almost completely it. She really just wanted to hear about him--kept badgering him, always wanting to know what happened. Maybe if he talked to her she could move on, but I don't think they'll have a romantic relationship in the future, though there probably will be some important interaction between them, because it just seemed unlikely that she would have such a large part in this book and then be nearly completely written out.
There won't be a Ron-Hermione or Harry-Hermione relationship, that would leave one of that threesome (no, there won't be anyo f those either 😮 ) as the akward third wheel. They're good friends, for pete's sake, not lustful lovers. The development of either of those romantic relationships would be totally cheesy, expected, and akward. No, thast won't happen. Viktor-Hermione might just happen though--the way Rowling subtly brings him into the story in number 5 may hint that his character will return later for a bigger role. I mean, it would be kind of pointless to have the guy still writing to Hermione in number 5, then just drop him later withou any further development. Rowling just wouldn't do that. As for Ginny's romantic future, who knows? I can say that I also think she will not end up with Harry, however. She's completely past that, and, no matter how much of a brave, strong, smart, clever, mature, repsectable character she's turning out to be, I think Harry wil lalways think of Ginny, to some extenet, as "Ron's little sister".