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it's implied that sarah will survive and might leave somewhere mid-season. from what i read, sarah's and grissom's relationship will come to a stand still somewhere in the middle of the season. i think that is where she might leave. maybe thats why they're keeping it tight lipped cause in a sense she's still signed thru season 8 just that for how long. and they do have a new female csi coming in...and insist that its not a replacement for sarah. but that is what i read from like 10 different sources. could all be a hoax, rumors, etc. don't know. but i guess its a good ploy in getting people to turn in during the premiere to see if she's axed or not.