8k is a sales pitch from a desperate industry.
4k, 8k, 3D... All gimmicks to get people to buy new TVs rather than run a set through its lifespan.
Most TV panels are rated for 50000 hours. If one watched 8 hours of TV each and every day that's 17 years and change operational life.
They want you to buy.
Hollywood *ahem* masters tiny little indie movies like, oh, Star Wars or all the Marvel Movies or Bill and Ted 3, etc at DCI 2K. Any "4k" Blu-Ray or stream coming from a studio is an upsample. Those last two sentences end all debate. No one needs 4k or 8k. The kids drank the Kool-Aid. (Also, I tease my friends at FXHOME because they do software tutorials at 4k 60fps. That extra temporal resolution doesn't make watching a mouse pointer moving around a software interface more exciting, but the Google algorithm gives creators better list placement for 60fps video, so... Have some Kool-Aid!)
The only gimmick they've tried to sell worth a damn is HDR10, and that's stalling out because nothing is produced at HDR10. Too bad. 10-bits/pixel gives 1024 value levels per RGB channel instead of 256. That extra color latitude for a 1080p picture makes a hell of a lot more difference in image quality (at a lower bandwidth cost) than just throwing more dots into the matrix.