One way the sports leagues might attack this is to argue that the casinos are using the leagues' trademarks, just as they go after anyone who mentions "Super Bowl" in advertisements.

Ontario, Canada, has sports betting - I just saw an ad for betting "pools," where you pick the winners of games on your preprinted ticket and the bettors with the most correct picks share a pool. They also have games called "Pro-Line" betting. http://proline.olg.ca/prolineEvents.do?ref=home_menu I notice they use abbreviations rather than team names, which probably insulates them from the trademark argument.