Signs are evident that the NFL has done permanent damage to its business by appearing to side with the Colin Kaepernick-initiated kneeling during the National Anthem.  My guess is that the owners of NFL teams collectively have lost billions, and I suspect that Roger Goodell will lose his job.  

Francis Turner calls our attention to a poll from Yahoo Finance:  

A new Yahoo Finance poll suggests the NFL has an enduring problem on its hands. Nearly 62% of 9,056 respondents told us they plan to watch less pro football in response to the anthem controversy. Thirty-six percent said they plan to buy less NFL merchandise, and 32% have chosen not to attend a game they would otherwise have gone to. Those findings all have financial implications for the NFL and its 32 team owners.

We wanted to limit our survey, conducted online via SurveyMonkey from Sept. 28-29, to people who patronize the NFL, and exclude people who have an opinion but don't watch football. So we only counted answers from people who describe themselves as pro football fans. Eighty-eight percent of respondents said they watch at least one game per week, with 46% of those saying they watch more than two games.

He adds:

While it is true that this is an online poll, the sample size is large (YUUGE even), and SurveyMonkey are known to be good are detecting and removing ballot stuffing attempts.

You can look at all of the results in graphic form here.

Here are the two that Turner calls "most brutal":

Almost half of the public would be pleased to see them suffer financially!  They are angry and no longer identify with those teams.

My guess is that the owners initially dismissed the thought of long-term damage because of their experience with the players' strike.  Lots of fans were upset, but they came back.  If that's why they thought – and still think – the fans will come back, they misunderstand the bonds that tie fans to their teams.  Becoming a fan involves identifying personally with a team and with all the other fans of the team.  Fans become a tribe of sorts, sharing a common identity and common hopes.  Part of the reason people like to go to games is the glorious feeling of togetherness, sharing thrills and disappointments.  They "affiliate" with the team.  

The flag, the National Anthem, and the nation itself are an even larger identity, vastly larger and more important.  The nation is a glorious tribe, one that is multi-racial and multi-everything, because it includes every American.  It is a tribe for which Americans have willingly died, in fact, whom we honor by standing for the National Anthem and saluting the flag.

When identities clash, people are forced to choose between them.

...or...

This doesn't describe every fan, but it describes a big share of them.  If the NFL loses only 20% of its revenue over the next few years, that is billions.

For decades, NFL owners were able to extract an ever increasing bonanza by raising ticket prices and from networks bidding against each other for broadcast rights, and corporate suites lulled them into believing that the public's appetite for their particular form of entertainment was insatiable.

The next time a team tries to extract taxpayer money for a new stadium, the opponents will outnumber the supporters, I bet.  Angry people write letters and attend protests.

In fact, it might be time for Congress to revisit the NFL's status as a nonprofit, which deprives the Treasury of a lot of money, I bet.

Baseball, once upon a time, was the most popular sport, earning the title "The American Pastime."

The NFL faces so many problems, from brain trauma liability to TV ratings, and has such a high overhead that the last thing it needs is to alienate a fraction of its fan base.