The future existence of the Arena Football League appeared in doubt Friday when NBC announced that it will not renew its revenue-sharing deal with the AFL and will no longer continue to televise its games. NBC had begun televising the out-of-season indoor football league after dropping out of the costly competition to air NFL games in 1998. But in recent years, ratings for the AFL games have failed to rise; indeed they have decline significantly. Last month the Arena Bowl -- the Super Bowl of indoor football -- scored only an 0.7 rating. What's more, NBC has signed a new deal with the NFL. In an interview with Saturday's New York Times, NBC spokesman Mike McCarley said, "We gave [Arena Football] our best effort, with top production and significant promotion, but the ratings never grew."