Sango-chan is not coming back to the chat, at least as it currently exists. I know what the consequences of that will be: I'll lose touch with her.
This has happened to me before, probably dozens of times. I've befriended somebody in a shared net-social context, and once one of us leaves that context, the friendship disintegrates from neglect. Most recently, I left a Matrix RP that was dying, and lost contact with all my friends from it.
It's happened to me in real life, too, a few times. The most dramatic was when my best friend Alex moved up the coast, to Northern California. I downloaded AIM and IMed him out of the blue one day, and we tried to keep the friendship alive; I even visited him a few times. But it didn't work. He's been off my buddy list for years.
More recently, when I changed schools to independent study, I lost most of my friends. I still have three, but they're in a lower grade, so my social context with them (wasting time playing video games) hasn't really been lost.
Actually, there's only one time this hasn't happened: my (current) best friend, Darci. We started as in-character boyfriend/girlfriend in a Trek chat on AOL; the in-character relationship died, and she stopped frequenting the room soon after, but the OOC one survived. But even here, I sometimes go weeks or months without talking to her--I'm actually in a down period now. And we've had several weeks of RL time together to reinforce our friendship, including two weeks staying at my house and a week shared on a vacation in England. (No, nothing happened, ecchis. She had an RL boyfriend at the time anyway. The closest we ever got was when we both were lying in my bed, under separate blankets, fully clothed, and not touching, while watching a DVD of First Contact on a jerry-rigged "DVD player" that was really a Pentium I with a DVD drive, decoder card and monitor.)
It's possible that such a thing could happen again, but somehow I doubt it. Darci leaving the room took most of the fun out of it, and so sticking with her ultimately meant sacrificing the community. But I don't think I'll sacrifice the community this time--the chats are still fun.
Especially with Shadow back. I don't know what it is, but at least so far her return has brought a lot of the missing fun back with it. Perhaps it's just the time of day, and the afternoon and evening will bring the frustration back with the idiots. But at least right now, I suspect it won't...I don't really know why. *shrugs*
So, despite the happy memory I brought up above (and believe me, it is a mood-booster), I'm still worried. Hopefully I'm worrying needlessly. Hopefully the chat will change to be to her liking, or she'll decide to rejoin anyway. Or maybe I'm wrong, and I'll be able to hold on to this community and this friendship at the same time.
But I'm not holding my breath.