I saw a drama in which the character was dating someone she was calling -san. But I think that once your bond is very strong you stop calling the person -san. I don't know, it's just speculation, we should ask someone who knows don't you think?
It's like all the NS fans who wish Sakura was calling Naruto "Naruto-kun" once NS will be canon, they don't get that it would be like their relation was decreasing. Not calling him -kun shows that they have a very strong bond, even if at first she didn't use suffixe for him because she didn't care about him enough to call him -kun, now she calls him Naruto without suffixe because they are close enough. Calling him -kun would be like they are less close than they are now. It's like Kushina was suddenly calling Minato "Minato-kun" just because they are married. It doesn't work like that.
Are there allot of fans who want Sakura to call Naruto by Kun? I thought that was in the minority, I hate the idea personally, I like it when Sakura calls him by just his name, I don't know why it irks me when ever I see fanfic, or Doujin where she calls him Naruto-Kun, it's the opposite with Naruto, because as far as i'm aware Sakura is the only person he used -chan with, everyone else it's either on a first name basis, or by thir title. the ones he cares for more get a nickname, Pervy-sage, Baa-chan, Teme, Sakura-Chan, Kakashi-Sensie, Iruka-Sensie, With everyone else he's first name basis as far as I know, Ino, Shikamauru, Neji, Lee, Hinata.