Is there a way to make level streaming work on the Z axis?


I’m working on an open world setup and using the extensive level streaming feature (which is amazing, by the way). The only thing is, I’d like to have streaming distance apply on the Z axis as well like in outer space. So far, it appears to only apply on the X and Y axes. Are there any plans to incorporate this? Or any plans to have the world composition map be 3 dimensional?