We go to DQ typically at least once during each visit. On longer trips, we go multiple times. Honestly, in the past 18 months, DQ has been fairly empty no matter when we visited, so I don't think you'll have much of a problem. In fact, I don't remember the day of the week it was when we were there last time, but it was in late June 2016. It was early afternoon when we went. It was so empty that nobody...not a one...was playing the huge hockey game (forget the name) for long stretches, the 4th and 5th floors were almost total ghost towns, we were walking around up there almost by ourselves.
Don't know if the announcement will cause crowds to get bigger, so they can see it one last time before it closes.