Granted, there's no indication at this point of what things will be like by late August (much less in a matter of days or weeks), but it's definitely a situation that Star Wars fans will be keeping in the back of their minds. That will especially be the case for those who have already secured passes or started looking into hotels and airfare, as the event traditionally draws fans from all over the world.
If Celebration Anaheim II did end up being postponed, it wouldn't necessarily be unprecedented for the convention to skip another year. Past Celebrations have often been scheduled around key events in the franchise, which has led to the con not being held on certain gap years. While Celebration Anaheim II would realistically have some big events tied around it - including the upcoming second season of The Mandalorian and the 30th anniversary of The Empire Strikes Back - we'll just have to wait and see if the event will be able to go on as planned.
Star Wars Celebration Anaheim II is scheduled to be held from August 27th through August 30th.