Just look at the NBA. ZERO positive tests. Zero, zip, nada. After 90+ days.
That's incredible knowing what we know about the transmission properties of this virus.
I just did some ballpark calculations: NBA players from all 30 teams is around 450. NFL players from all 14 playoff teams is 714 players. So 264 more players in the NFL Playoffs. Honestly, I think that is doable, especially if you make two bubbles, one for NFC and one for AFC like another poster mentioned.
The Super Bowl becomes a problem, as they players are going to have to travel. But with testing and following all CDC guidelines, they should be OK for one game.