I don't know if there's a point to anything beyond UHD Blu-Ray disks. How much further improvement is there to go in further reducing compression artifacts, or color space (and they do support 4k60, right?)
8k video seems like only the realm of standing directly in front of a screen in a show room, to me.
Though I'm personally at a point where I barely buy media any more. Most of my recent media purchases have been on Amazon streaming.
The video quality leaves much to be desired (especially when it switches to low-bandwidth mode, and I've got gigabit internet, so I know that the problem isn't on my end) but it plays on everything (and more importantly, *everywhere* so long as I have an internet connection) and doesn't take up space.
I also don't really watch (most) movies more than once, so rentals are appealing. With the death of the video store, that means either new releases from Redbox (which look better, but include the hassle of having to return them), or anything else from a streaming service.