I have been thinking about reasons for Universal's radio silence on this, when they could be hyping this up but leaving Hagrid's Magical Adventure in the dark. And I think I have it.
Uni knows fans miss BTTF & they still have the Delorean, Train, & Doc Brown meet & greet. No doubt they measure the popularity of these things. Now, what if the “high-energy Universal franchise” is BTTF? Heck there's still interest & with what Universal did bringing back Kong, we know they are okay with re-purposing their original lineup! I feel like this could translate VERY well to a live action stageshow, but they are tight-lipped because literally no one is expecting this.