That is sort of funny. They said the same thing about baseball once.
Was baseball ever really as popular on a national level as the NFL is today? And I do mean on a truly national level. In the so-called "Golden Era" of Major League Baseball, which I generally see described as being roughly from the end of World War II until the Dodgers and Giants folded after the 1957 season, it would surely be debatable to what degree either baseball OR the NFL was truly a "national sport." Baseball had no teams west of St. Louis and many of baseball's cities still had two local teams throughout this era (St. Louis with the Browns and Cardinals, Chicago with the Sox and the Cubs, Philadelphia with the A's and the Phillies, New York with the Dodgers, Yankees, and Giants, Boston with the Braves and the Red Sox). Football never really began its ascendancy as a national sport until the 1960s with the rise of televised football. I think there's a fair argument that the sports marketplace changed so profoundly with, most importantly, the ascendancy of television and, secondly, the nationwide expansion of the professional leagues (made possible by the advent of jet aircraft) that it's impossible to compare the popularity of, and marketplace for, pro sports prior to roughly 1960 with what's come later.
I think there's also a fair argument that with the rise of cable television and the Internet, and the concomitant rise of 24-7 sports coverage and the ever-growing number of outlets for sports coverage, there's far more room for many more sports to succeed than there ever used to be. Back in the days when you had three major TV networks plus a PBS channel there simply wasn't room for all the sports we see today. The rise of cable TV, and the debut of sports networks, to some degree fueled the growth of additional sports because the new channels needed something to cover. (Anyone else remember how for quite a few years ESPN had a morning show covering Wall Street because there simply wasn't enough sports programming to fill the whole day?) Would Arena Football, for example, have been even remotely imaginable back in the days when there were just the three broadcast networks?
Let me hasten to say that I'm not disagreeing with your proposition that, as a theoretical matter, it's certainly possible for the national taste in sports to change. College football used to be far more popular than the NFL and I think it's fair to say that's changed. Baseball once got far more attention than football and that's changed too. But I think the marketplace for sports is now so utterly different from what it was back then that it's hard to compare those days to now.
