A lot depends on what happens when some states open up schools for in-person instruction. That will start happening in a few weeks. If that happens without major complications in COVID hospitalizations, then I think the NFL season will probably limp along for at least some games. It will be like watching the replacement-level stuff in 1987 when practice squad guys have to play a lot more when starters have to sit out for positive COVID tests and for getting hurt for not being in football shape like they usually would be. It's probably going to be terrible football, but there's too much money at stake not to complete a season of some sort if at all possible. I'm trying to envision the Super Bowl next February being played in an empty stadium with a halftime show being held in front of about 100 people sitting in the stands.
If schools open back up and some older staff or extended family members of kids start getting hospitalized and dying, then everything that involves team sports will probably get shut down. I desperately hope this doesn't happen, but a lot will depend on people wearing masks and not sending their kids to school if they get sick (which will force them to miss work and lose pay).
There have been some recent articles by public-health officials saying that if we were really serious about getting this under control, we'd shut everything back down from now until Labor Day. Six weeks would be enough to get this under control everywhere and it would allow most schools to open and the economy to get going again in September. August is a downtime for a lot of people anyway, so take advantage of it. Of course, we know this is never going to happen.