If I were to speculate what a new portal to the "Wicked of OZ" land/portal would be, I would create an area broken down into 3 sub areas; Emerald City, Shiz University and and area known as "the west".
You'd enter the portal and be transported to Shiz University. This is where you will find attractions like the Glinda and Elphaba meet and greet that starts off as a dorm tour/walk through. It will also feature an Intamin dynamic motion stage themed to the Oz Dust Ballroom/Dancing Through Life.
A quick service dining location and shopping experiences.
The Emerald City will feature more shopping and a table service with quirky and unique food choices. I'd love to have a wave swinger or hot air balloon flat ride located here as well.
Here is where I will take a bold move, located inside the wizard's castle will NOT be a stage version of Wicked but instead a dark ride "book report" in the likes of frozen ever after/the voyage of the little mermaid. Id say trackless but universal hasn't had much experience in that field yet. I would probably have a little boutique for little girls to get all glinda-fied or go green like elphaba.
The West would be indoors. I would want this area to be similar to Knocturn alley. This would be a hideaway for the animals that did not confirm and were they have set up settlement. Inside, I would have and indoor version of F.L.Y at Phantasialand themed to the flying monkeys.
It will traverse above and below you in the indoor area. We aren't talking about a huge flyer, something that's about 40ft difference in elevation, 2 launches. A few shops and snack locations around the perimeter of the inside area to leave the middle for the coaster and themed forest area. Maybe a couple small family flat rides.
This is what I speculate an OZ/Wicked land should be if Universal decides to pull the trigger!