My guess would be that overwhelming majority of people signing up at SV aren't so much leaving SB as just making sure they aren't missing any conversation/stories.
Personally, I'm primarily at SB for the fanfic. If an author I'm interested in announces that he's moving to SV and never posting again to SB, I'd add that to my list of sites to care about; otherwise, not going to bother (and, to be honest, since splitting content between two sites doesn't add any real value, I'm kind of hoping this doesn't happen).
If it stays at "people who are butthurt at SB" level, it's unlikely to have much staying power. A particular problem with that theme is that it will attract people who were banned from SB for good reason, which means you could easily end up with a forum badly in need of immediate heavy-handed administration but whose raison d'etre is a protest of heavy-handed administration.
If you're the sort of person who cares about this kerfluffle, then odds are you really care about it, which would distort a bit your perception of the situation. I'm going to guess that, for most members, the response is "Who? What?"
Personally, I'll just be glad when this blows over and I don't have to see those oversized signatures that everyone who cares about this seems to think are needed. If I don't care that "Athene didn't resign!", I'm not going to care about it any more when it's in a 24-point font.