There is a good old trick of culling anything behind a certain distance and then putting fog so that culled "nothing" can not be seen. What if a game engine would utilize pre-rendered 360' panoramic spheres or boxes and use them as skybox or going a much more complicated way - rendering such panoramas not just as a diffuse texture but ones also having depth-buffer info so the game objects in the far could be sorted by depth and occluded by those skybox "objects" correctly, like monsters other players, cars etc. If went even further there would be like 2 - 5 spheres one inside each other to enhance the parallax effect being constantly updated but not as often as the main screen does so the performance on the main screen doesn't drop down that much...
Of course there must be a big load of such panoramas scattered and tied up closely together in the 3d space grid, pre-rendered or rendered in the game process.
Some modern games substitute distant 3d models with sprites, like Far Cry 5 does it with trees and it worked pretty nicely as far as I remember.
