I don't understand why anyone cares about Netflix 4K. Their regular HD video bitrate maxes out at 3.9Kbps, apparently.[1] Their "Super HD" takes you up to 6mpbs. OTA television signals are at 18mbps.[2] And Blu-Ray can go up to 40mbps.[3] Increasing the number of pixels without increasing the bitrate doesn't really fit any more actual picture info into the stream.
The 18Mbps OTA signals you mention are MPEG2. Netflix is AVC. Anything above 6Mbps AVC is pointless because the quality differences become indiscernible. You need to start tuning things like frame rate and filters at that point.
Keep in mind that OTA television is using MPEG-2 instead of the more advanced H.264 video codec - roughly double the bitrate for the same quality.
As well, OTA is somewhat inefficient with duplicated frames, as all 1080i content is broadcast at 1080i60, whereas Netflix can encode content to the original frame rate (i.e. 1080p24).