Comcast Corp’s NBC News plans to launch an online streaming service this year as part of its effort to reach younger viewers who prefer to watch their favorite shows online. The median age of “NBC Nightly News,” for example, is 64 years old, according to Nielsen. Comcast NBCUniversal invested $500 million in Snapchat owner Snap Inc during its initial public offering. Despite its increased focus on digital, NBC News has no plans to bring any of its content back to Facebook Inc.