It will also be interesting to see the court cases that come from what American governments have done so far; there's a serious case to be made for violations of our right to freely assemble. Even the time, place, and manner standard (which is still contested but is current precedent) may not cover such drastic curtailment of all public gatherings.
Sadly, these things usually happen and get fought out in court later (see Japanese internment camps) when in some sort of crisis state, so I doubt constitutionality has any bearing on the pencil-pushers latest and greatest idea.
Friendly reminder that, while I don't see any malicious intent in the current actions, these directives specifically sound disturbingly close to those issued by many an authoritarian government:
> You cannot engage in group activities in person with others.
> You cannot have dinner parties. You cannot invite friends over to your home to hang out.
The precedent set today could be abused in the future, particularly precedent that looks like this.