I have absolutely zero inside information, but I can pretty much guarantee none of those proposals are happening lol.
What I would pitch to Universal is a thrill ride version of The Great Movie Ride, with the ride vehicle being the DeLorean, with your tour guide being Steven Spielberg (or Robert Zemeckis).
You would be sent back in time to major events in Universal Studios history, like its founding by Carl Laemmle, the first monster movies, early animation, their successes in the 70's and 80's, etc. But then one of the cartoon villains breaks out of his movie, steals your plutonium, and strands you in the past.
It's up to the studio crew and your favorite characters to create a lightning bolt of 1.21 gigawatts to send you back home, reset the timeline, and save the studio!