Spanish-language media giant TelevisaUnivison unveiled a surprise overhaul of its ad-sales structure Monday — with just weeks to go before the TV industry opens its annual “upfront” marketplace. The company replaced Tim Naividad, who had been in place since June of 2025, with a veteran internal choice, John Kozack , who has worked at TelevisaUnivision over two decades. Natividad had previous experience at Roku and Amazon, and his digital chops were no doubt welcome at a traditional media company that has recently made significant strides in streaming. And yet, the move suggests TelevisaUnivision couldn’t abandon its reliance on the millions it generates from linear TV. The company’s advertising revenue in the fourth quarter came to $856 million, flat with results from the previous year. In the U.S., advertising revenue declined 11% to $423 million.…