agreed with much of what's been posted above. I for one would love a scenario where Sora once again is out of commission or separated from Donald and the Goofster, and they end up with Kairi. It doesn't even need to be a playable situation, just a few scenes popping in with those three; they've got a lot of common ground! No better way to strengthen Kairi's relationship with Sora than by having her connect with the people closest to him.
That and she was basically with Sora for the duration of his KH1 adventure, so she knows them better than you think she might.