To make that initiative more difficult, it was just announced that original cast member Marg Helgenberger will also be leaving the show. Helgenberger, who played Catherine Willows in over 250 episodes, will remain on CSI for a final stretch until January. She was originally going to leave after last season, her 10th, but agreed to stay a bit longer to allow the writers to wrap-up the story of Catherine Willows appropriately. Her final appearance will be in Season 11, Episode 12.
Losing Petersen caused a big drop in ratings, and it's safe to assume that losing Helegenberger will do the same. It's nearly impossible to successfully replace such mainstays. Now all of the pressure is on Ted Danson to revive the show, or worse, sink with the ship.