The Samsung Galaxy S6 may just receive Android Oreo
Android updates are privileges for the most part, with most OEMs only sending out one major OS update, and the best of them doing a maximum of two. A user on Reddit has supplied images of his chat with a Samsung service rep that point towards the Galaxy S6 receiving Android Oreo in the near future.
The S6 was released way back in 2015, so this would be something of an anomaly—no other OEM sends out major updates to three-year-old devices. In fact, it's so far out of the norm that we doubt its actual viability. A major reason for update cycles lasting just two years is Qualcomm, as the chipset manufacturers only support drivers for a two-year period. That, however, is not a factor here, as the S6 snubbed the Snapdragon 810 due to its many issues, instead opting for the in-house Exynos 7 Octa 7420.
Chat reps aren't the most concrete sources of information, so there's a chance this comes to nothing, If the S6 is actually billed for Oreo, we wouldn't be surprised to see updates pushed out by early Q2 2018.
Thanks to /u/CyberConCoder for bringing this to light! Here are screenshots of their chat.