If I knew what was going to be a hit, I’d be out in L.A. making big money as a studio executive! The question is, who knows? And the answer is: no one will, for a couple of months. Elementary got 13 million viewers for its first episode, which in the words of TVbythenumbers is “solid,” not terrible but not as good as say, The Mentalist’s pilot and first season ratings (also a show based on Sherlock Holmes, that was the previous resident of Elementary’s time slot) or the ratings of another new CBS drama, Vegas. Its ultimate fate will be decided based on how it does over the next couple of months consistently and what other shows CBS has in the pipeline.
In U.S. TV, there are so many episodes in a season that they look at more of the long term ratings. With CBS, I think if it averages 12 million or more per week it will probably be renewed, anything lower than that and it might be at risk. That’s based on Unforgettable, a CBS drama from last year, which got 14 million viewers for its pilot but was then cancelled when it ended up only averaging 11-12 million viewers week to week (thought they’re bringing it back as a limited summer series next year).
As for affecting Sherlock, you have nothing to worry about! If Elementary is still on the air next year, it still won’t compete with Sherlock, as they are on at different days and times, and Sherlock is on PBS, which is not in competition with the broadcast networks. Sherlock and Downton Abbey are the PBS crown jewels: they not only get record ratings, but they’ve garnered such critical acclaim and received so many awards that they’re solely responsible for the press PBS is now getting about being the new HBO or AMC. Sherlock will have a home at PBS as long as it (and PBS) continue to exist. Which is my nice segue into reminding U.S. Sherlockians that our real worry is what will happen if Romney gets elected.