Cumulus Media’s KNBR 680 is dropping ESPN Radio and will be among the first affiliates of a new radio sports network being launched by CBS early next year. KNBR and sister station AM 1050 fill their off-peak hours with ESPN shows such as “Mike & Mike,” Colin Cowherd, “Nick and Artie” and “JT The Brick.” CBS is promising to deliver to its affiliates a “full lineup” of programs. What that means for KNBR isn’t known. The switch to CBS was decided at Cumulus headquarters in Atlanta, which signed up 67 of its stations with the new network.