[U: They will] Galaxy S8 and Note 8 Reportedly May Not Get OneUI Interface
UPDATE 12/11/2018: Samsung confirmed that a handful of its older devices would be getting the new One UI. This includes the Galaxy S8, Galaxy S8+, and the Galaxy Note 8.
Although the focal point of yesterday’s Samsung Developer Conference was their much-awaited Infinity Flex technology on their foldable smartphone, Samsung also took to the stage to officially present their new design language OneUI. A OneUI-based Android Pie update for the Galaxy S9, Galaxy S9+ and Galaxy Note 9 is in the works and is expected to roll out in January next year. Due to the keynote's abrupt ending, it’s unclear whether the Galaxy S8, Galaxy S8+, or Galaxy Note 8 will receive the new One UI interface. The new UI may not be coming to older devices like the Samsung Galaxy S8 and the Samsung Galaxy Note 8 according to a Samsung spokesperson who spoke to Tom’s Guide.
“Disappointingly though, Samsung has confirmed to Tom’s Guide that the Galaxy S8, S8+ and Note 8 will miss out on this new modernized and streamlined software experience.” – Adam Ismail, writing for Tom’s Guide
Samsung has previously confirmed that Android Pie would be coming to the Galaxy S8, Galaxy Note 8, and a few other mid-rangers. It seems unlikely that Samsung would backtrack on releasing Android Pie for the Galaxy S8 or Galaxy Note 8. Perhaps, the Galaxy S8 and Note 8 could receive an Android Pie update based on Samsung Experience.
The prospect of Samsung releasing two different iterations of Android Pie for different devices seems absurd as it would mean Samsung has to maintain multiple versions of their Android Pie software, which is cumbersome even for a company with Samsung's resources. But, a version of Samsung Experience 10-based Android Pie already exists, so the theory could still hold water. Perhaps the Samsung representative conveyed an incomplete message. The Galaxy S8 and Note 8 are more than capable of running OneUI, so it's hard to tell at this point.
Source: XDA developers