Your experience about high school baseball games struck a chord with me. That's what I found with regards to Junior B hockey games.
For the uninitiated, Junior B is one step below the junior league that I follow - the Ontario Hockey League.
When I would go to a game, I think I'm probably the only one who actually paid for a ticket. The rest of the crowd are parents and friends, who likely got their tickets on comps from the players.
The only one in the OP's post that I will comment on is the NHL.
Even if players are allowed back in training camps, they will need at least 3 weeks to condition and get in game shape. This was as per Gary Bettman - the commissioner.
My response?
Just cancel the rest of the season and the playoffs already.
That's what the Canadian Hockey League did with the playoffs of the respective leagues (Quebec, Ontario, Western) and the Memorial Cup.
The commissioner of the Quebec league said it wouldn't be until early 2021 when the Q gets going again. The president of the 3 leagues, who is also the commissioner of the Ontario League, was aware of what the commission of the Q said. The president is still optimistic that the Ontario league will open up as normal to start the 2020-2021 season. Training camps start in the last week of August.
I think that's a little ambitious. I think it's still WAY too early to start opening things back up. It could take one spike in the number of new cases, and we'll have to start all over again.
Joker's Wilde