Well that is a risk, but it does come down primarily to the marketing I think. If you give it the right kind of an ad campaign and are talking with the press about the content in the right way, you'll draw in the crowds that enjoy mature television. Think "Platoon" or "Apocalypse Now" as a TV show, not imagine it as a show in the Alien universe. The horrors of a prolonged fight against the aliens. Lots of symbolism, with varied and interesting characters, and the people being the focus. The aliens would return to being that silent enemy that slips in, devastates, and slips out.