I dunno, a bunch of healthy 20- and 30-somethings who think that they are gods among men are probably willing to roll the dice for salaries ranging from high six figures to low-mid seven figures. So if the public doesn’t care, the seasons will go on. The issue is containing outbreaks so that there are enough healthy players to field a team.
This is a big challenge for football, because meetings throughout the day break out by position group. As a result, losing 20% of your roster for a month to COVID-19 probably doesn’t mean losing a WR, a TE, two OL, two DL, a LB, and three DBs. It probably means losing 7 OL and 3 DL or something like that, and most teams only carry 7-8 offensive lineman. It’d be virtually impossible to win with 5 offensive lineman off the street, and it’d be franchise malpractice to put a franchise QB out there behind 5 offensive lineman off the street.
I don’t know how they avoid this. It’s going to happen to someone. If I were an NFL GM, I’d have a backup QB in total isolation, working out and practicing with a couple coaches that are also in total isolation. My entire practice squad would be offensive and defensive lineman, and I’d also isolate them from the rest of the team.