I think the NBA and NHL have the right plan in place with their "bubble". Whether the players stay within the bubble is another story. So far it seems like the bubbles are working and there aren't a ton of positives coming from those leagues.
I think the NFL is going to keep a very close eye on what happens with MLB. The Marlins having an outbreak this early in the season could be very telling. If they can contain it and get it under control without it spreading to other teams that could be encouraging for the rest of the season and for the NFL teams.
The protocols the NFL has in place seem to be pretty solid with their testing, cleaning, tracking, etc. I would still definitely say its doubtful they will finish the season.
College football is going to be a total train wreck if they go forward with it.