A press release from Apple display supplier LG in 2015 said that Apple would release an 8K iMac later that year. Didn’t happen and probably won’t happen this year. But by 2020, it’s a possibility.
In 2014, Apple debuted the iMac with 5K display (with a resolution of 5120 x 2880 pixels). Currently, it makes little sense for Apple to release an all-in-one with even higher resolution.
LG's 8K display technology is dubbed "Quad Ultra-High Definition," with a resolution of 7,680 by 4,320 pixels. That's two times the resolution of a 4K screen, with four times the number of pixels. But what would be the point of an iMac with such a screen? According to a report from the Strategy Analytics research group, it will be another couple of years before 50% of U.S. homes even own a 4K TV.
Yes, 8K resolution is the highest ultra high definition television (UHDTV) resolution to exist in digital television and digital cinematography. Still, it's one thing to "future proof" a product and another to add future proofing that won't be practical for at least a year or two.
But it will eventually happen — though an 8K iMac or 8K Apple display won’t come cheap (LG has previewed an 88-inch 8K TV that’s expected to cost over $100,000). Juniper Research forecasts that 8K smart TV shipments will grow more than threefold between 2020 and 2021, to reach over 400,000 per annum by the end of the forecast period. And Dell sells the UP3218K, a 31.5-inch 8K IPS computer display. It costs $5,000, so expect any 8K Apple products to be in that price range, if not higher.
It will probably be several years before 8K displays become commonplace, but don't be surprised if you see companies like Apple selling ‘em in the near future.