There’s pretty much no point to 8k.
Talk to me in 5 years.
He’s kind of right in that it’ll make zero difference for anything shot on less than an 8K camera, even for most film-based content. Also, hardly anybody can see pixel structure with 4K displays at normal viewing distances, so adding more pixels isn’t going to improve the experience in a meaningful way for most people. 4K already gave us the most noticeable improvements with HDR, a wider color gamut, and higher frame rates.
I have a 27" 5K monitor and I have to put my eyes within a few inches of the screen to make out even the faintest pixel structure. At about 20" away, which is my normal viewing/working distance and where the screen takes up a significant portion of my field of vision (like sitting close at the theater, but not too close), there’s no discernible pixel structure at all.
I’d be willing to bet that a 4K HDR recording of a front-seat roller coaster ride at 120fps on a large screen would be enough to cause motion sickness and vomiting in many people. How much more realistic does it need to be?
I say this as an avid A/V enthusiast.
Back on topic: I still haven’t seen STD and won’t buy it on disc, but I’d gladly add DS9 in HD to my collection, right alongside my TNG and TOS Blu-rays.