Not necessarily. A large potential audience means large ratings expectations that Star Trek cannot meet. A niche strategy might be the smarter move. Those networks have specific demographic strategies that are poor matches for Star Trek. CW = girls and women, 18-30 or thereabouts. CBS = casting a wide net for Middle America by creating lowest-common-denomentator programming. Star Trek appeals disporpotionately to males, and it doesn't appeal to Middle America. Of all the networks, the best demographic match is FOX. But all the networks are too broad appeal/non-nichey for Star Trek so cable is a better bet. You obviously haven't checked the ratings if you're using that show as a successful example of a sci fi show. ABC renewed it to save face because its entire 2009-10 lineup would have been a bust otherwise and it didn't suck quite as badly as the rest of the options. It's not about ratings. It's about expectations of ratings. Viewership levels that constitute an abject failure on CBS are a stunning success on cable. Context is everything. But yeah, it does have to be good. One heartening trend lately is how intolerant audiences are of flawed shows like V, FlashForward and Heroes. When shows start to suck, or suck from the start, they are rewarded with cancellation. Good for us. We should have to put up with shit.