Comcast said Monday it will appoint President Michael Cavanagh as co-CEO, adopting a dual chief executive model as the company prepares to spin off several NBCUniversal cable networks as part of a restructuring.Cavanagh will take up the new role in January and also join the company’s board, serving alongside Brian Roberts, who will continue as chairman and co-CEO.Several high-profile firms such as Oracle and Netflix have adopted a co-CEO model to better manage their operations as they become more complex an ...