Add AT&T to the list of media giants launching streaming services that revolve solely around their own content. The company's WarnerMedia is launching a streaming offering in the fourth quarter of 2019 with access to the group's collection of movies and TV shows. Most details are under wraps, but CNN has obtained an internal memo from CEO John Stankey showing that it would "start with HBO" and "package" Turner and Warner Bros. content. And while it would be a stand-alone service, Stankey stressed that it would "complement" the company's conventional TV distribution. It's trying to avoid a fight with cable and satellite giants worried they'll lose customers, in other words.