Disney is usually pretty good abotu timing and getting things done by their time... If I were you though, I would still try to make this Res for as late in your trip as possible, so to let them work out the issues with just reopening
My DH asked me to make reservations for Teppanyaki but we will be there from 8/27 to 9/4 and I'm afraid they won't be open. I'm going to keep my Le Cellier reservation and if Teppanyaki is open when we are there I'll try to change my ADR then.