I'm confused too. Some people have been told its going dark after Labor Day (7th), some have been told the 13th. But it's still showing on the calendar. I'm just hoping it stays on the calendar and they decide to postpone the work they need to do until after my trip.
For those of you who listen to waht Al Lutz has to say on the subject, here was an update from the 1st:
Editor's Note 8/1: Flotsam & Jetski's night vision cameras are working well, and Murphy the Fantasmic dragon is meshing with his new programming, which has emboldened Disneyland to add two Fantasmic shows per night back to the weekend schedule in September, at least until HalloweenTime begins.
It's the latest I have heard on the matter, so maybe we will be getting Fantasmic on the weekends in September still. Maybe not. We still don't know.