I doubt it, but I so want it to be Nodoka. That aside, when he said he "talked to her" I was thinking someone like Setsuna, so who knows. Maybe it IS just respect as opposed to a literal romantic interest.
Either way, I'm still a fan of Negi x Nodoka and in the school roster, he did write "cute" for her picture. He's never done that with any of the other girls.
The girl I find it most likely to not be (if it is in a romantic manner) is definitely Asuna. To me, he treated her too much like a surrogate sister. In all honesty, they've always put off a sibling-like vibe to me.
Let's see...what else...oh yes, must say I love Chisame's character. I do like the fact she's one of the most human characters of the series despite the zaniness around her.