I'd love to see the ratings since Sara, Warrick, and now Grissom have departed. I bet there wasn't much of a hit without the first two, but I can't see them holding up with the main character now just a memory. While I'm here, who decided that the Riley character would work as a viable replacement for Sara/Warrick? She belongs on Miami or New York maybe, but doesn't have the talent or presence to be anything more than totally one dimensional.
Just my opinion.
The ratings have been just as strong and consistent as they were before Grissom, including when Sara left. The News file thread posts the ratings every week.
Grissom's final episode had large ratings only due to the fact it was his final episode and people who probably haven't watched in awhile, came back to watch his exit.
I disagree that the show is going to fail without Grissom. In the beginning they may have gone to Grissom for advice and such, but Grissom himself said "I have no more students to teach" (or something like that). The CSI's pretty much worked with Grissom as equals for a number of seasons now.
However, time could tell, but I don't think it will fail as the show has maintained its numbers in ratings.
Now, I do agree with you concerning Riley. Though I like the brother/sister thing that they seem to have going on between her and Greg, she just bugs me. Maybe that will change, but I'm doubting that.
I think LF has what it takes to maintain the show. I mean we're going to get overkill from him because he is the male lead, but I like his character and his fans will come to watch too.