the removal of tessellation is a major oversite. No disrespect intended. While the intent is to build all data directly into the mesh, the blend/detail phase now has to be done externally and assembled into one mesh set then import into unreal.
yes in practice that looks better but in a practical production standpoint that’s ridiculous and time consuming. this puts alot of weight and issue on the front end. for instance, if i want to blend a brick wall over a large area with blended brick variation and damage, this is now impossible with nanite inside unreal. i’ll need to blend this data in something like Blender or Houdini or zbrush, and take that into unreal.
ya that’s… “cool” …but really bad for production times. Ideally we need to be able to blend/tesselate then convert that data to nanite. Im surprised epic didn’t encounter this possibility. unless theres a workaround we don’t know about yet???
If not, thats a bad call. but im sure they have something up their sleeve in the coming weeks/months. 
Fingers crossed