Cryengine 5 Already does this, Will this feature turn up in Unreal Engine anytime soon?
http://docs.cryengine.com/display/CEMANUAL/Integration+of+Object+Meshes+into+Terrain+Mesh
We actually had a conversation with @ZeroNight on discord about it not so long ago. It is really cool feature alone, but when coupled with rendering terrain with soft depth test it bocomes even more powerful. These two features provide awesome synergy together and allow amazing terrain/landscape mesh blending.
So does that mean it is coming at some point in the future or is it one of those things that has to be in like an Epic game to be put in the engine, if that makes sense