Yeah, I understand why movie theaters are interested in 5k, but I don't think most people will be able to see the difference on home televisions.
Not that that will stop them from making them, but it'll be interesting to see what happens after 4k/5k when the limit of how much resolution the human eye can perceive has been surpassed.
Marginal improvements in apparent resolution aren't the only thing that a more efficient codecs can deliver. The same capacity can also be used to increase the bitrate of the encoded files dramatically, and / or deliver streams at much higher frame rates. In terms of improving picture quality, jacking up these aspects while keeping resolution at less than the supported maximum can be far more effective places to spend your bit budget.
Not that that will stop them from making them, but it'll be interesting to see what happens after 4k/5k when the limit of how much resolution the human eye can perceive has been surpassed.