Here's some properties that are listed on the Universal Brand site that I would qualify as evergreen.
-E.T.
-Classic Monsters
-Jaws
-Jurassic Park
-Back to the Future
-Fast and the Furious
-King Kong
-Shrek
-Despicable Me
-SNL
All from very different time periods and genres. I think the issue with Universal is that they did come out the gate with a lot of their own heavy hitters, but the nature of having a theme park with limited space necessitates getting rid of stuff to bring in new attractions to bring in more guests. And when the most pressing attractions for replacement are with some of the only attractions representing your biggest franchises, I get why there is desire to bring stuff back.
I get why the original Jaws, BttF, Kong, Shrek attractions are gone, but that doesn't mean that a Shrek dark boat ride or a Back to the Future coaster or Peter Jackson-inspired Kong Party Bus would be a bad idea in the slightest. Even representing these franchises in something like the Epic Movie Ride idea would go a long way in building identity for Universal Studios as a brand. Most of the major attractions at Uni theme parks are outside IPs, that doesn't have to be the case. There is a lot to work with here.
To be fair to Universal, they have been investing in additions to this core lineup with Kong, Velocicoaster, Monsterland, Villaincon, HTTYD Land. Fast was a flop that would've been on the list had they put effort into it, but hey! They seem keen on preserving E.T. for the time being, that's nothing to sneeze at! I think we'll see a lot more movement in this direction that we think. Nintendo and Potter will still be a priority, but Uni is making strides here.