I don't think there will be much of a hit (yet) in terms of expected crowds. Currently there are no (reported) cases in Orange county, and there are no travel advisories to the area.
I have been checking hotel availability to see if it looks like there are major cancellations happening. For example, a few weeks ago looking at RPR I saw there was no available rooms for a family of 4, where as now when I check I can see there are some 2 queen rooms available. And so while there are undoubtedly be some people cancelling their trips last minute, I don't think it's going to be a significant difference. Maybe 1 point on the crowd calendar scales at best (i.e. if a crowd calendar is predicting a 9/10, it may in actuality be an 8/10).
Next week is March break for most of Canada and many people go to Orlando during that timeframe (as I'm sure from many places in the US also having spring break period). But with the cost of these vacations being quite high, most will not cancel last minute and lose all of that money unless they are forced not to go (a new Travel ban, parks close etc.)
Now if you have a cruise booked, that's a different story.