The league has been fortunate until now.
There is no Tennessee Titans-Pittsburgh Steelers game on the schedule because there has been a COVID-19 outbreak among Titans personnel. Last Sunday, the Titans played the Minnesota Vikings and positive tests came back. The National Football League initially let the Steelers know that it has planning to push ahead with the game. Then the league thought about postponing it a day or two, then the league finally decided to just postpone it to another week and hope for the best. The COVID-19 outbreak was in week four, so schedules can be rearranged but for a league that is highly dependent on television revenue this year, the playoffs may become a problem for not only the NFL but TV and marketing partners if there is a COVID-19 outbreak on a playoff team. The NFL has playoff games scheduled for January 9th, 10th, 16th, 17th, 24th with the Super Bowl taking place in Tampa on February 7th. The league also has its Pro Bowl Game slotted on January 31st. Just one playoff team having a COVID-19 outbreak could cause NFL chaos and with no vaccine on the horizon until the spring according to the scientific community, it is possible the NFL may not be able to stick to its plan.
The NFL and its players did reach an agreement to attempt to get through the season during the pandemic. There were no preseason games and the league got really lucky with few positive tests. The National Hockey League got through its playoffs with no COVID-19 problems, the NBA has gotten to the finals. Major League Baseball and Major League Soccer have had some COVID-19 cases. Golf and tennis players have contracted COVID-19. The NFL is headed into colder weather and there is a major worry that with the arrival of colder weather and the flu season, COVID-19 will be a major problem. The NFL could be in a crisis mode.