It's weird - there are a couple people on the show that, if they died, I would have a hard time watching. Even though Marg and Billy are the frontrunners, CSI is really an ensemble show. I can't imagine it without most of them. I think if Brass or Greg died it would be hard for me to watch - they both just add so much to the dynamic. I think if TPTB had chosen to kill Sara off before GSR, it might have been a little easier. As it stands now, I don't really want to watch the show without Sara and with Grissom in mourning. Although, now that I think about it, Sara dying would give Billy a reason to get out of CSI after Season 8. Hmm.
In any event, Sara is my favorite character and I can't see myself enjoying the show without her. I could even go without GSR and still watch - I just really love her character and it would be really horrible if she died.