Oh, no source -- just my own take.
I'm guessing any congregation -- at casinos, concerts, sporting events, airports, railway stations, theme parks, etc. -- can't really happen again until there's a vaccine and it's broadly distributed.
Whether there are legal restrictions or it's just a natural fear-based response by average individuals, I just don't see how humans will allow Petri dishes to re-form unless they're convinced that they and their families are basically safe from the virus.
Locally, small groups/clusters can re-form. A restaurant with a limit on guests and tables six feet apart. People will be willing to interact with others who have been tested and are negative before a vaccine, so they'll go out with friends.
Schools I'm not so sure about -- there will be immense pressure to re-open in the fall given the relative lack of death risk among the young, but I'd guess it's touch-and-go at least here in the USA.
It's a very extreme perspective, I recognize -- I'm not at all sure I am right.