The Macy's Parade is the only thing I can be really sure about being cancelled since they currently do not have parades running right now already. They occasionally take out a float and have characters dance around though. There is a possibility they might do something littler like that for Christmas.
Concert is hard to say since the concerts that were cancelled was when Universal was closed period. However, due the fact that all concerts everywhere are cancelled pretty much until 2021 and the area of that section is massive it would be hard to keep and eye and control that section anyway to keep people socially distancing so that would be out more than likely.
Considering that technically they still have shows and make sure to keep everyone apart with gaped seating (like Bourne). I can see that Grinchmas show can continue since it's a certain section where they can mark places to watch from (like Beat Builders / Blues Brothers) and could have enough TMs to monitor the people to make sure they socially distance. It's not a massive area where the show is taken place so I think it's manageable.
If anything, like all the other characters, The Grinch would be on a stage and pose for photos and what not like the others are doing right now. Maybe he can shout a few things at people?
Keep in mind these are all theories. Those are the only things I can see potentially being affected. I would imagine that they'd keep all the decorations out as normal. Either way, if they take a lot of things away, I'm sure they'd do other things instead rather just take everything away. Like how this year for Halloween how
HHN was cancelled, but they at least opened a couple of haunted houses for day guests and encourage costumes (which they never done before).
