Is any sort of LOD planned?
I mean, those chunks missing their meshes: it would look nicer if instead of holes you rendered solid "plugs" as high as the highest block of the chunk missing its mesh yet. Then retract them into the ground smoothly after the mesh is generated.
Also, there could be other ways: (Planet Explorers had this implemented): LODs like, in the distance meshes are built by joining 8 adjacent blocks into one -- this way you can have a 4-chunk LOD mesh at the price of one.