After doing some soul searching (AKA browsing MK Wiki), I think I finally have a solid wishlist for stages:
Earthrealm: Pretty much self-explanatory. There are plenty of locations you could have as a stage, such as maybe the abandoned headquarters of the Black Dragon, maybe a stage from the White Lotus Society, or a stage from the Lin Kuei headquarters. Personally, I would love to see a snow stage of some sort of this realm, considering we've only had something like a few times before
Outworld: When it comes to Outworld stages, fantasy and magical elements are the name of the game. The dangerous and barbaric nature of the realm has been represented pretty accurately in the past with stages like Living Forest, and now they could take a things step further by making a huge, outside stage with dragons and other mystical, winged creatures flying in the background and maybe even Shadow Priests guarding the area
Netherrealm: Being Mortal Kombat's equivalent to Hell, stages of this realm should obviously reflect the torturous and evil nature of the realm. There could be a stage on the Netherrealm's 5th plane, a barren wasteland type of stage with fiery cliffs, large, flowing rivers of lava, and violently erupting volcanoes in the background. You could also have Shinnok's throne as a stage or another stage in the city of Nekros, where a
Festival of Torture could take place in the background
Edenia: I would like to see a stage of the ruins of the royal battlefield that the 10th Edenian Mortal Kombat Tournament took place on. There would be dilapidated Edenian statues, just like with Jade's Desert, and since I envision this battlefield being near the castle of Jerrod and Sindel, the background could show an outside view of the abandoned castle, maybe showing a few of the royal yet worn-out Edenian designs and patterns decorated all over the outside of the castle
Seido/Orderrealm: Stages in this realm should reflect the pristine, orderly and antiseptic nature of the realm. I picture Seido being proficient in both technology and magic to an extent. A central pyramid hub that connects to all of the other pyramid structures as seen in the Konquest mode of Deception could be the stage; the other pyramids would be higher in elevation and be far off in the background. The stage would also obviously be in the sky. Seidan Guardsmen could appear in the background and the pyramids would have neon designs to them just like in Deception
Chaosrealm: A stage here could feature the many floating rock formations, temples and water structures found all throughout the realm
Shujinko has also already gone on the quest; he began the quest years before the events of MK1 so it's impossible to prevent it