Update | Purported EEC document may refer to OnePlus 6T
Update: The leak is now thought to be false.
Given the OnePlus device-release pattern of the last few years, the 6T could be released some time around November 2018. A new document linked to a Russian regulatory agency has given slight weight to this estimation. Its text contains reference to a new OnePlus device model number, the A6013. This also fits in with the company's conventions for new releases.
The OnePlus 6 is also known as the A6000, or A6003 for the Eurasian and North American markets. Similarly, the OnePlus 5 is the A5000, whereas the 5T is the A5010. Therefore, it follows that this document, reported as coming from the Eurasian Economic Commission (EEC, which is based in Moscow), is the non-Asian variant of the 6T. On the other hand, the document does not contain any other information about its subject's specs, operating system or other attributes, as is normal with this type of leak.
Nevertheless, it is reasonable to assume that this version of the OnePlus 6T (assuming the leak is accurate in this respect) will ship with Oxygen OS based on Android Pie. At this point, we still do not know much about this device. However, it is being speculated that the 6T will come with the waterdrop-style notch recently pioneered by OPPO. Some other concepts circulating in the media suggest that OnePlus will also finally embrace wireless charging for their next flagship. However, the company's CEO, Pete Lau, has shot this line of inquiry down in the past, possibly in favor of the proprietary wired fast-charging system found in OnePlus phones.