According to the sources, Burke's contract doesn't expire until the end of 2020, but he could leave his post before then. If that happens, Shell, who is based in Los Angeles, would split his time between New York and the West Coast when he assumes the role of CEO.
These potential changes would follow Burke's major reorganization of NBCU in January that put Shell in a prime position to replace him.
Despite the rumors, another insider told the magazine that no plans had been finalized for either Burke's departure or his successor.
Burke has been CEO of the entertainment giant since January 2011. Before that, Burke was chief operating officer of Comcast, whose acquisition of a majority stake in NBCU led to Burke's transition to becoming the chief executive of the network.