Hi, Marcia!
Thanks for stopping by the Moms Panel!
I sure wish we had a definitive answer for you on this. See, when construction is going on, it's really hard to say which areas will remain open and we won't know until it is announced by the folks at Disney.
If you're wanting to purchase tickets for the
Tomorrowland Terrace Fireworks Dessert Party, the best thing to do is to keep checking for your date at about 90-days out. I have found that when you call Disney Dining at 407.WDW.DINE [939.3463] and speak directly with a Cast Member, they can sometimes see availability in their system that you may not be able to see online if that makes sense. I wouldn't count on it, but it never hurts to ask. They'll also be able to let you know if a certain date is unavailable due to being sold out or if the event isn't taking place that particular evening.
I sure hope this helps. Please don't hesitate to write back in if we can help with any other questions you have.
Wishing you a Pixie Dusted vacation!
~Jackie