I found it very thought-provoking that the conversation shifted from speculating about what likely will be in Universal's Epic Universe, to would the park open with only part of what the artist map representations show. This led to, a general discussion along the lines of (USO wouldn’t do something like that / Oh but Volcano Bay kind‘a sort’a did) then drifted to another subject.
Well... back when USF, the original park, in Orlando was ready to official open, with I4 packed with dozens of billboard showing Ghostbusters, Jaws, Kongfrontation, Earthquake-The Big One, ET Adventure and few other of their main attractions, it looked like they had a hit on their hands. Best I can remember is ET Adventure , Universal Orlando's Horror Make-Up Show and maybe Ghostbusters (Anyone know if it did?) were the only major attractions that managed to be ready for the June 7, 1990 Opening Day. Also... Jaws, Kongfrontation and Earthquake: The Big One opened, but were mostly NOT OPEN. It took about a year to get the Kongfrontation and Earthquake: The Big One opened for real. That leave Jaws and it turns out that Jaws was so messed up, that the ride had to be evacuated often, Universal made many attempts to get Jaws 1.0 to work but it never happened, and Jaws 1.0 closed for good. A new Ride & Show Engineering company was hired to come up with a WORKING version of Jaws. Jaws 2.0 official opened just before summer tourist season 1993.
So would Universal's Epic Universe open with major attractions missing? Not a chance. There is no way Universal Orlando Resort would ever wish to go through that humiliation again, or giving away massive numbers of FREE comeback any time tickets to hordes of unhappy guest.