I have no inside info, but you bring up an interesting point.
Universal has been very strange about announcing details in relation to closing attractions. Potter, Transformers, and Volcano Bay (major projects, although Transformers less so) had announcements happen far after construction started, much less attractions closing.
Yet F&F and Fallon had announcements occur before attractions closed (both kinda major, I suppose).
So, either Universal is sticking to this format of major attractions having construction before announcements, or the announcement + closure model is the new standard.