I thought that it would be a nice idea to incorporate a 3D Network Trace. It might be easier to do simply because there already exists a network trace for 2D features. I am working on a 3D project and I would like to be able to do a network trace in 3D since I am working on a model that includes several 3D line features. I think this would be a good benefit to the 3D webscene capabilities since webscenes are still relatively limited. I am hoping ESRI will continue to expand more in the 3D webscene environment.