Bloomberg: The Summer Olympics ratings slip, the first since 2000, raises fresh doubts about what used to be a sure thing: live sports would be a huge and growing draw no matter what. That’s why NBC parent Comcast paid $12 billion for exclusive U.S. broadcast rights to the Olympics through 2032. Others, including Disney’s ESPN, 21st Century Fox, Time Warner and CBS, have made long-term bets on football, baseball and basketball.