No character meet and greet's either.
I wonder the impact to the parties and after hours events, I mean those are more limited in attendance any way. But at least half the fun of Halloween party is the special fireworks, and parade, not to mention the special characters. I'd guess trick or treating is out too.
I think the mask thing will be harder for people in the US than it was in Shanghai, people in many Asian countries are more used to wearing them for dealing with smog and such already.