Veteran programmer Rob Barnett recently attended a breakfast meeting of television executives where the talk turned, as it almost always does these days, to “disruption,” the industry buzzword for the way new technology is upsetting the TV applecart. From somewhere down the table, he heard a question: “Has anybody here cut the cord?” — that is, dropped cable service in favor of just watching TV through the Internet? Barnett shrugged and raised his hand. “Mine was the only one,” he recalls. “But when it went up, I saw beads of sweat break out on the foreheads of some of the...