Wrong.
Wrong on every level.
The physicality of the game isn't what makes the NFL the NFL, it's the fact that they play 1 game a week, and it's a single elimination tournament to determine the champion. Add in the fact that players are on non-guaranteed contracts (meaning they're willing to play through missing limbs to get their next pay day), and you have guaranteed drama and intensity no matter who's playing.
Surprise surprise--America's other sporting obsession--March Madness, follows a similar structure. Single elimination tournament with guys playing for that NBA pay day.
But for the rest of the sports landscape? With people having 1000 cable channels to chose from, the days are long gone of people sitting down to watch 162 baseball games, or even 82 nba/nhl games, for that matter.
Please don't take the opinions of the posters on here to be a cross section of American life--the NBA does not rule the sports landscape. It's a nice alternative to the NFL, but it's not like it's in a neck and neck race with them.
Now, the demise of the NFL will come when other sports realize that, and adjust their schedules accordingly. If the NBA stopped guaranteeing contracts, and the teams played 24 games a year, with a single elimination tournament to determine a champion--it would take over the NFL in popularity in 5 years. NBA cities would be building bigger arenas, putting 100,000 people in a gym to watch a wild card game.
If you disagree, that's fine, but all things considered--the NFL actually puts the worst product on the field of any of the 4 major sports. Everything is reviewed, there are too many commercial breaks, the officiating is way too inconsistent, injuries keep star players out of the game from the day mini camps open, teams are eliminated from playoff contention before Halloween because such a small subsection of teams make the playoffs, and those that do are often times inferior division winners who are making it at the expense of wild card teams that have more talent--like the Cardinals last year, or anyone from the AFC central or west this year (barring the raiders). The NFL itself has BEEN broken, but drama sells.
Once the other 4 major sports address the folly of best-of-sevens in this day and age, we can begin to discuss the downfall of the NFL