Yes, there is. There's always a National Championship Game, played between the teams ranked highest after all the 'normal' games, including individual conference finals, have been completed. So, there's always a champion crowned at the end of a season.
Now, the ranking of these teams is often contriversial, especially if more than two teams end up with identical record - Indeed, this season, up until a week or two ago, it looked quite liekly that three, or even four teams might have finished the season undefeated, which would have led to choas in deciding the championship game. Many who don't like the current, non-playoff based set up actually openly desire such an end of season picture, though it's not happened yet.
Now, the ranking of these teams is often contriversial, especially if more than two teams end up with identical record - Indeed, this season, up until a week or two ago, it looked quite liekly that three, or even four teams might have finished the season undefeated, which would have led to choas in deciding the championship game. Many who don't like the current, non-playoff based set up actually openly desire such an end of season picture, though it's not happened yet.